Top 68 Slang For Crazy – Meaning & Usage

Sometimes, regular words just don’t cut it when you want to describe something that’s beyond normal. That’s where slang for “crazy” comes in. We’ve gathered the wildest and most creative words and phrases that people use to express their excitement, amazement, and pure insanity. Get ready to dive into this listicle and discover the craziest slang out there!

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1. Bonkers

This word is used to describe someone or something that is completely crazy or out of control.

For example, “The party last night was bonkers! There were people dancing on the tables and throwing drinks.”
A person might say, “I can’t believe she quit her stable job to become a circus performer. She’s totally bonkers.”
In a discussion about a wild roller coaster, someone might comment, “That ride is absolutely bonkers!”

2. Loony

A term used to describe someone who is mentally unstable or acting in an irrational or foolish manner.

For instance, “He’s been acting really loony lately. He keeps talking to himself and laughing for no reason.”
In a conversation about a bizarre conspiracy theory, one might say, “Only a loony would believe something like that.”
A person might exclaim, “You want to jump out of a plane without a parachute? Are you completely loony?”

3. Nuts

This word is used to describe someone or something that is mentally unstable or behaving in a bizarre or irrational manner.

For example, “She went nuts when she found out her favorite band was coming to town. She started screaming and jumping up and down.”
In a discussion about a chaotic situation, someone might say, “It was absolute nuts! People were running in all directions.”
A person might comment, “I can’t believe he ate a whole jar of hot sauce. He’s nuts!”

4. Cuckoo

This word is used to describe someone who is mentally unstable or behaving in a crazy or eccentric way.

For instance, “She’s always talking to her imaginary friend. People think she’s a bit cuckoo.”
In a conversation about a strange fashion trend, one might say, “Who would wear shoes with fish swimming in them? That’s cuckoo.”
A person might exclaim, “You want to climb Mount Everest without any training? Are you cuckoo?”

5. Wacko

This word is used to describe someone who is mentally unstable or behaving in a bizarre or irrational manner.

For example, “He went wacko when he found out his favorite team lost. He started throwing things and shouting.”
In a discussion about an unconventional art piece, someone might say, “That painting is so wacko. I can’t make sense of it.”
A person might comment, “I can’t believe she dyes her hair a different color every week. She’s totally wacko!”

6. Nutty

This term is used to describe someone or something that is mentally unstable or behaving in a strange manner.

For example, “He’s always coming up with nutty ideas.”
A person might say, “That movie was so nutty, I couldn’t follow the plot.”
Another might describe a situation as, “Things got a little nutty at the party last night.”

7. Batshit

This term is an intensifier for the word “crazy” and is used to describe someone or something that is extremely irrational or mentally unstable.

For instance, “She went batshit when she found out he had cheated on her.”
A person might say, “That conspiracy theory is batshit crazy.”
Another might exclaim, “The boss went batshit and fired everyone in the department.”

8. Barmy

This term is primarily used in British slang to describe someone who is slightly crazy or eccentric in their behavior or thinking.

For example, “He’s a bit barmy, always talking to himself.”
A person might say, “I can’t believe she did that, she’s completely barmy.”
Another might describe a situation as, “The whole idea seems a bit barmy to me.”

9. Mad as a hatter

This phrase originated from Lewis Carroll’s “Alice’s Adventures in Wonderland” and is used to describe someone who is completely insane or mentally unstable.

For instance, “After the accident, he went mad as a hatter.”
A person might say, “She’s been acting mad as a hatter lately, talking to imaginary friends.”
Another might exclaim, “You must be mad as a hatter if you think that’s a good idea.”

10. Off the wall

This term is used to describe something or someone that is extremely unconventional, eccentric, or strange in their behavior or thinking.

For example, “His ideas are always off the wall, but sometimes they actually work.”
A person might say, “That performance was completely off the wall, I’ve never seen anything like it.”
Another might describe a situation as, “The conversation took an off the wall turn and no one knew what to say.”

11. Cray cray

This term is a playful way of saying “crazy.” It is often used to describe someone or something that is extremely wild, unpredictable, or out of control.

For example, “She went cray cray when she found out she won the lottery.”
A person might say, “That party last night was cray cray!”
Another might exclaim, “I can’t believe how cray cray that movie was!”

12. Demented

This word is used to describe someone who is mentally unstable or insane. It suggests a severe disturbance in a person’s mental state.

For instance, “He’s acting demented, talking to himself and laughing uncontrollably.”
A person might say, “The killer’s demented mind led him to commit heinous crimes.”
Another might describe a chaotic situation as, “It was pure demented madness!”

13. Psycho

This term is used to describe someone who is psychotic or mentally unstable. It implies a person who is dangerous, unpredictable, or exhibiting abnormal behavior.

For example, “Stay away from him, he’s a psycho.”
A person might say, “She went psycho and started smashing everything in sight.”
Another might describe a character in a horror movie as, “The psycho killer was terrifyingly deranged.”

14. Whacko

This word is used to describe someone who is crazy or eccentric. It suggests a person who behaves in a bizarre or unconventional manner.

For instance, “He’s a total whacko, always coming up with strange ideas.”
A person might say, “The artist’s work is so whacko, but that’s what makes it interesting.”
Another might describe a person’s outfit as, “She’s dressed like a whacko with all those mismatched patterns.”

15. Bonkersville

This term is used to describe something that is crazy or insane. It implies a state of extreme madness or chaos.

For example, “The party last night was absolute Bonkersville!”
A person might say, “I can’t believe how Bonkersville this roller coaster ride is.”
Another might describe a person’s behavior as, “He’s gone completely Bonkersville with his conspiracy theories.”

16. Loopy

This slang term refers to someone who is acting in a strange or eccentric manner. It can also be used to describe something that is bizarre or unconventional.

For example, “She’s been acting really loopy lately, talking to herself and wearing mismatched socks.”
In a discussion about a strange event, someone might say, “That’s a loopy idea, but it just might work.”
A person describing a weird movie might say, “It’s a loopy film that will leave you questioning reality.”

17. Nutter

This slang term is used to describe someone who is mentally unstable or behaves in an irrational or unpredictable manner. It is often used in a derogatory way.

For instance, “He’s a complete nutter, always saying bizarre things and acting out.”
In a conversation about a person’s strange behavior, someone might comment, “I think he’s a bit of a nutter, to be honest.”
A person describing a wild party might say, “It was full of nutters doing crazy things.”

18. Crazypants

This slang term is used to emphasize someone’s level of craziness. It is often used in a lighthearted or humorous way.

For example, “She’s always coming up with crazypants ideas that no one else would think of.”
In a discussion about a chaotic situation, someone might say, “It was crazypants in there, with people running around and screaming.”
A person describing a wild adventure might say, “We had a crazypants night, doing things we never thought we would.”

19. Batty

This slang term is used to describe someone who is slightly crazy or eccentric. It can also refer to something that is odd or unusual.

For instance, “She’s a bit batty, always talking to her plants and believing in conspiracy theories.”
In a conversation about a strange fashion choice, someone might comment, “That hat looks a bit batty, don’t you think?”
A person describing a quirky friend might say, “He’s a bit batty, but he’s always entertaining to be around.”

20. Nutso

This slang term is used to describe someone or something that is extremely crazy or insane. It is often used to emphasize the level of craziness.

For example, “He went completely nutso when he found out he lost his job.”
In a discussion about a chaotic event, someone might say, “It was absolute nutso, with people screaming and running in all directions.”
A person describing a wild party might say, “The atmosphere was nutso, with everyone dancing and jumping around.”

21. Insane in the membrane

This phrase is used to describe someone or something that is mentally unstable or behaving in an irrational manner. It is often used in a light-hearted or humorous way.

For example, “After the roller coaster ride, I felt like I was insane in the membrane.”
A person might say, “My boss’s demands are driving me insane in the membrane.”
In a funny situation, someone might comment, “That joke was so bad, it made me feel insane in the membrane.”

22. Cuckoo bananas

This phrase is a playful way to describe something or someone that is extremely crazy or absurd. It is often used to emphasize the level of craziness in a situation.

For instance, “The traffic during rush hour is cuckoo bananas.”
A person might say, “Her outfit was so wild, it was cuckoo bananas.”
In a conversation about a chaotic event, someone might exclaim, “It was pure cuckoo bananas!”

23. Wacky

This word is used to describe something or someone that is eccentric, unusual, or out of the ordinary. It is often used in a lighthearted or positive way.

For example, “He has a wacky sense of humor.”
A person might say, “I love her wacky fashion sense.”
In a discussion about a bizarre invention, someone might comment, “That’s a wacky idea!”

24. Madhouse

This term is used to describe a place or situation that is chaotic, disorganized, or out of control. It can also refer to a mental institution or psychiatric hospital.

For instance, “The shopping mall during the holiday season is a madhouse.”
A person might say, “The office was a madhouse after the announcement.”
In a conversation about a crowded concert, someone might comment, “It was a total madhouse!”

25. Cracked

This slang term is used to describe someone who is mentally unstable or behaving in an irrational or unpredictable manner. It can also refer to something that is broken or damaged.

For example, “He’s cracked, he talks to himself all the time.”
A person might say, “I think the stress has cracked her.”
In a funny situation, someone might comment, “That joke cracked me up!”

26. Bananas

This slang term is used to describe someone or something as being extremely crazy or insane.

For example, “That party last night was absolutely bananas!”
A person might say, “I can’t believe she did that, she’s totally bananas.”
Someone might describe a chaotic situation as, “It was pure bananas in there!”

27. Out of your mind

This phrase is used to describe someone who is behaving in a completely crazy or irrational manner.

For instance, “You’re out of your mind if you think I’m going to do that.”
A person might say, “I was so angry, I was out of my mind with rage.”
Someone might describe a wild idea as, “That’s completely out of your mind!”

28. Bizarre

This term is used to describe something as being strange, unusual, or out of the ordinary.

For example, “I had the most bizarre dream last night.”
A person might say, “The fashion at that event was really bizarre.”
Someone might describe a peculiar behavior as, “His actions were so bizarre, I couldn’t understand why he was doing that.”

29. Lunatic

This slang term is used to describe someone who is perceived as being mentally unstable or crazy.

For instance, “Don’t listen to him, he’s a complete lunatic.”
A person might say, “She’s acting like a total lunatic, I don’t know what’s gotten into her.”
Someone might describe a person’s erratic behavior as, “He’s been acting like a lunatic lately.”

30. Crazed

This term is used to describe someone or something as being wildly out of control or obsessed with a particular idea or thing.

For example, “The fans were crazed with excitement when their favorite band took the stage.”
A person might say, “He’s crazed with jealousy over his ex’s new relationship.”
Someone might describe a chaotic scene as, “It was a crazed frenzy of people pushing and shoving.”

31. Off your rocker

This phrase is used to describe someone who is mentally unstable or acting in a crazy manner. It implies that the person has lost their sense of reality or reason.

For example, “He’s completely off his rocker if he thinks he can fly without wings.”
In a discussion about unusual behavior, one might say, “She’s a bit off her rocker, but in a lovable way.”
A person describing a chaotic situation might say, “The party last night was completely off its rocker.”

32. Nutcase

This term is used to describe someone who is mentally unstable or exhibits strange or irrational behavior. It is often used in a lighthearted or joking manner.

For instance, “Don’t mind him, he’s just a nutcase.”
In a conversation about eccentric individuals, one might say, “She’s a total nutcase, but she’s always entertaining.”
A person describing a bizarre event might say, “I witnessed a real nutcase on the subway today.”

33. Zany

This word is used to describe someone who is unconventional, eccentric, or unpredictable in their behavior. It suggests a sense of humor or quirkiness.

For example, “He’s always coming up with zany ideas.”
In a discussion about unique personalities, one might say, “She’s a bit zany, but in a good way.”
A person describing a comedic performance might say, “The comedian’s zany antics had the audience in stitches.”

34. Madcap

This term is used to describe someone who is wild, reckless, or impulsive in their actions. It suggests a disregard for consequences or a willingness to take risks.

For instance, “He’s always getting into madcap adventures.”
In a conversation about daring individuals, one might say, “She’s a madcap thrill-seeker.”
A person describing a chaotic situation might say, “The party turned into a madcap frenzy.”

35. Deranged

This word is used to describe someone who is mentally disturbed or mentally ill. It implies a severe or extreme level of craziness or irrationality.

For example, “He’s completely deranged, you can’t reason with him.”
In a discussion about unstable individuals, one might say, “She’s a deranged lunatic.”
A person describing a violent act might say, “The deranged gunman caused chaos and panic.”

36. Screw loose

This phrase is used to describe someone who is mentally unstable or has unusual behavior. It suggests that the person has a “screw loose” in their mind, meaning that something is not quite right.

For example, someone might say, “He’s got a screw loose if he thinks he can fly.”
In a conversation about odd behavior, one might comment, “She’s always doing strange things. I think she’s got a screw loose.”
Another might jokingly say, “You must have a screw loose to go bungee jumping.”

37. Maniac

This term is used to describe someone who is crazy or behaves in an unpredictable and wild manner. It can be used both affectionately and derogatorily, depending on the context.

For instance, someone might say, “He’s a maniac on the dance floor!”
In a discussion about extreme sports, one might comment, “Only a maniac would try base jumping.”
A person might jokingly refer to themselves as a maniac, saying, “I’m a maniac when it comes to eating spicy food.”

38. Absurd

This word is used to describe something that is ridiculous, nonsensical, or completely unreasonable. It implies that the situation or idea is so far-fetched or illogical that it is difficult to believe.

For example, someone might say, “It’s absurd to think that aliens built the pyramids.”
In a conversation about strange laws, one might comment, “It’s absurd that it’s illegal to walk your pet lobster on a leash.”
Another might say, “The prices at that fancy restaurant are absurd!”

39. Unhinged

This term is used to describe someone who is mentally or emotionally unstable. It suggests that the person is “unhinged” from reality or normal behavior.

For instance, someone might say, “She became completely unhinged after her breakup.”
In a discussion about erratic behavior, one might comment, “His unhinged actions were a cause for concern.”
A person might describe a chaotic situation as “unhinged,“unhinged,” saying, “The party turned into an unhinged mess.”

40. Wild

This word is used to describe something that is crazy, unpredictable, or out of control. It implies a sense of excitement or chaos.

For example, someone might say, “Last night’s party was wild!”
In a conversation about extreme weather, one might comment, “The storm was wild, with strong winds and heavy rain.”
Another might say, “The concert was wild, with the crowd jumping and singing along.”

41. Frantic

This term describes a state of extreme excitement or worry, often characterized by rapid and chaotic movement or behavior.

For example, “She was in a frantic rush to finish her project before the deadline.”
In a chaotic situation, someone might exclaim, “Things are getting frantic around here!”
A person describing their busy day might say, “I’ve been running around all day, it’s been absolutely frantic.”

42. Cracked out

This slang term is used to describe someone who is under the influence of drugs and exhibiting erratic or bizarre behavior.

For instance, “He was so cracked out, he was talking to imaginary creatures.”
In a conversation about drug abuse, someone might say, “I’ve seen people completely cracked out on the streets.”
A person describing a wild party might say, “Things got really cracked out after midnight.”

43. Nonsensical

This word describes something that is illogical or lacking in meaning or sense.

For example, “His argument was completely nonsensical.”
In a discussion about a confusing movie plot, someone might say, “The storyline was so nonsensical, I couldn’t follow it.”
A person describing a bizarre conversation might say, “We ended up talking about nonsensical topics for hours.”

44. Freaky

This term is used to describe something that is strange, unusual, or unconventional in a way that may cause surprise or discomfort.

For instance, “That horror movie was so freaky, it gave me nightmares.”
In a discussion about supernatural phenomena, someone might say, “I’ve had some freaky experiences that I can’t explain.”
A person describing a strange encounter might say, “I had the freakiest encounter with a stranger on the subway today.”

45. Hysterical

This word describes a state of extreme emotion, often characterized by uncontrollable laughter or intense fear or excitement.

For example, “The comedian’s jokes were so funny, the audience was in hysterics.”
In a situation where someone is laughing uncontrollably, a person might say, “She was absolutely hysterical, couldn’t stop laughing.”
A person describing a terrifying experience might say, “I was hysterical with fear when I saw the spider crawling towards me.”

46. Mad as a March hare

This phrase originates from the behavior of hares during their mating season in March, where they exhibit erratic and frenzied movements. It is used to describe someone who is acting in a wild or irrational manner.

“After drinking too much,“After drinking too much, he started dancing on the table and singing. He was mad as a March hare.”
“She was mad as a March hare when she found out her car had been towed.”
“The professor’s theories were so unconventional that some thought he was mad as a March hare.”

47. Coo-coo

This term is a colloquialism derived from the sound made by a cuckoo bird. It is used to describe someone who is behaving in an irrational or nonsensical manner.

“He’s been acting coo-coo lately,“He’s been acting coo-coo lately, talking to himself and wearing mismatched socks.”
“The artist’s eccentric paintings were often described as coo-coo.”
“She must be coo-coo to believe that conspiracy theory.”

48. Cray-cray

This term is a slang abbreviation of the word “crazy,” emphasizing the level of insanity. It is often used in a playful or lighthearted manner to describe someone or something that is extremely eccentric or unconventional.

“Her dance moves on the dance floor were so cray-cray,“Her dance moves on the dance floor were so cray-cray, everyone was in awe.”
“The roller coaster ride was cray-cray,“The roller coaster ride was cray-cray, with twists and turns that left riders screaming.”
“He’s always coming up with cray-cray ideas for his artwork.”

49. Out of one’s mind

This phrase is used to describe someone who is behaving in an irrational or unhinged manner. It implies that the person has lost touch with reality or is no longer thinking clearly.

“After the accident,“After the accident, he was out of his mind with grief.”
“She went out of her mind when she saw the spider in her room.”
“The stress of the situation made him feel like he was out of his mind.”

50. Screwball

This term is used to describe someone who is unpredictable, odd, or eccentric in their behavior or ideas. It can also refer to something that is strange or unusual.

“He’s a real screwball,“He’s a real screwball, always coming up with bizarre inventions.”
“The movie had a screwball sense of humor,“The movie had a screwball sense of humor, with wacky characters and absurd situations.”
“Her fashion sense is completely screwball,“Her fashion sense is completely screwball, with mismatched patterns and bold colors.”

51. Daft

This slang term is often used to describe someone who is acting in a silly or foolish manner. It can also be used to describe something that is absurd or ridiculous.

For example, “He’s always pulling daft pranks.”
Someone might say, “That’s a daft idea, it will never work.”
In a conversation about a ridiculous situation, someone might comment, “It’s daft how much drama there is over such a small issue.”

52. Cuckoo for Cocoa Puffs

This phrase is used to describe someone who is extremely crazy or obsessed with something. It is often used in a lighthearted or humorous way.

For instance, “She’s cuckoo for Cocoa Puffs when it comes to collecting comic books.”
A person discussing their love for a particular TV show might say, “I’m absolutely cuckoo for Cocoa Puffs over that show.”
In a conversation about someone’s eccentric behavior, one might comment, “He’s gone completely cuckoo for Cocoa Puffs.”

53. Batshit crazy

This slang term is used to describe someone who is completely insane or mentally unstable. It is often used in a derogatory or exaggerated manner.

For example, “That guy is batshit crazy, he thinks he can fly.”
A person describing a chaotic situation might say, “It was like a batshit crazy party, everyone was out of control.”
In a discussion about someone’s irrational behavior, one might comment, “She went batshit crazy when she found out he cheated on her.”

54. Loco

This Spanish slang term is commonly used in English to describe someone or something as crazy or mad. It can also be used to describe someone who is eccentric or unpredictable.

For instance, “He’s gone loco, he’s been acting really strange lately.”
A person describing a wild night out might say, “It was a loco party, everyone was dancing on the tables.”
In a conversation about someone’s impulsive decision, one might comment, “He’s always doing something loco without thinking about the consequences.”

55. Doo-lally

This British slang term is used to describe someone who is mad or insane. It is often used in a lighthearted or playful manner.

For example, “He’s gone doo-lally, he’s been talking to imaginary friends.”
A person describing a crazy adventure might say, “We had a doo-lally time exploring the abandoned house.”
In a discussion about someone’s eccentric behavior, one might comment, “She’s a bit doo-lally, but in a lovable way.”

56. Gaga

This term is used to describe someone who is acting in a crazy or eccentric manner. It can also refer to someone who is obsessed with something or someone.

For example, “She went gaga over the new celebrity gossip.”
A person might say, “I feel so gaga after staying up all night.”
Another might describe a friend as, “She’s always gaga about her favorite band.”

57. Cray

This is a slang term used to describe something or someone as crazy. It is often used in a playful or exaggerated way.

For instance, “That party last night was cray!”
A person might say, “I can’t believe how cray my boss is.”
Another might exclaim, “You’re driving me cray with your constant pranks!”

58. Wackadoodle

This term is used to describe someone who is extremely eccentric or crazy. It is often used in a lighthearted or humorous way.

For example, “He’s a total wackadoodle, always coming up with wild ideas.”
A person might say, “I feel like I’m going wackadoodle trying to meet all these deadlines.”
Another might describe a chaotic situation as, “It was a wackadoodle scene with people running everywhere.”

59. Fruitcake

This term is used to describe someone who is crazy or mentally unstable. It is often used in a derogatory or mocking way.

For instance, “Don’t listen to him, he’s a complete fruitcake.”
A person might say, “She went fruitcake after losing her job.”
Another might describe a bizarre behavior as, “He’s acting like a total fruitcake.”

60. Loonball

This term is used to describe someone who is crazy or eccentric. It is often used in a playful or affectionate way.

For example, “He’s such a loonball, always making everyone laugh.”
A person might say, “I felt like a loonball dancing in the middle of the street.”
Another might describe a friend as, “She’s a loonball, but she’s the most fun person to be around.”

61. Bats in the belfry

This phrase is used to describe someone who is mentally unstable or crazy. It originates from the idea of bats flying around in the bell tower of a church, symbolizing chaos or madness.

For example, “Don’t listen to him, he’s got bats in the belfry.”
When discussing eccentric behavior, one might say, “She’s a bit strange, definitely has bats in the belfry.”
In a humorous context, someone might joke, “I think I have a few bats in my belfry today.”

62. Wackjob

This term is used to describe someone who is extremely eccentric or mentally unstable. It implies that the person’s behavior or thinking is abnormal or irrational.

For instance, “Stay away from him, he’s a total wackjob.”
When discussing someone’s odd habits, one might say, “I can’t believe she collects toenail clippings, she’s a real wackjob.”
In a lighthearted manner, someone might jokingly refer to themselves as a wackjob, saying, “I’m a total wackjob when it comes to organizing my sock drawer.”

63. Nutjob

This slang term is used to describe someone who is mentally unstable or exhibits strange behavior. It implies that the person’s actions or thoughts are irrational or eccentric.

For example, “I can’t believe he climbed a tree naked, he’s a total nutjob.”
When discussing someone’s obsession with conspiracy theories, one might say, “He’s a real nutjob, always talking about aliens and government cover-ups.”
In a casual conversation, someone might refer to a friend’s quirky behavior, saying, “She’s a bit of a nutjob, but that’s why we love her.”

64. Dippy

This term is used to describe someone who is a little bit crazy or eccentric. It suggests that the person’s behavior or thinking is unusual or peculiar.

For instance, “She’s a bit dippy, always wearing mismatched socks.”
When discussing someone’s forgetfulness, one might say, “I’m so dippy, I forgot my own phone number.”
In a playful manner, someone might tease a friend, saying, “You’re such a dippy person, always getting lost in your own thoughts.”

65. Cracked in the head

This phrase is used to describe someone who is mentally unstable or crazy. It implies that the person’s mind is damaged or not functioning properly.

For example, “Stay away from him, he’s cracked in the head.”
When discussing someone’s erratic behavior, one might say, “I can’t understand why she did that, she’s clearly cracked in the head.”
In a joking manner, someone might playfully insult a friend, saying, “You’re a bit cracked in the head, but that’s why we love you.”

66. Wackadoo

This term is used to describe someone who is behaving in a strange or unpredictable manner. It can also be used to refer to something that is absurd or outlandish.

For instance, “She’s a total wackadoo. You never know what she’s going to do next.”
In a discussion about a bizarre fashion trend, someone might say, “That outfit is wackadoo.”
A person might exclaim, “This party is wackadoo! There’s so much craziness going on!”

67. Cuckoo-bananas

This slang term is used to emphasize the level of craziness or insanity. It is often used in a humorous or exaggerated way to describe something or someone that is beyond normal levels of craziness.

For example, “That roller coaster was cuckoo-bananas! I screamed the whole way.”
A person might say, “I can’t believe she did that. She’s absolutely cuckoo-bananas.”
In a discussion about a wild party, someone might comment, “The night was cuckoo-bananas. You wouldn’t believe the things that happened!”

68. Nutter butter

This slang term is used to describe someone who is perceived to be mentally unstable or crazy. It is often used in a lighthearted or playful manner.

For instance, “He’s a total nutter butter. You never know what he’s going to say.”
In a conversation about a person’s eccentric behavior, someone might say, “She’s a bit of a nutter butter, but she’s harmless.”
A person might jokingly refer to themselves as a nutter butter, saying, “I must be a nutter butter to do something like that!”