Top 57 Slang For Insane – Meaning & Usage

“Insane” may be a word that’s thrown around casually, but the slang associated with it can be a whole different ball game. From trendy terms to quirky phrases, our team has dug deep to uncover the most popular and intriguing slang for “insane” that’s currently making waves. Get ready to expand your vocabulary and impress your friends with this listicle that’s sure to keep you in the loop!

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1. Bonkers

This slang term is used to describe something or someone that is extremely wild, irrational, or out of control. It is often used in a lighthearted or playful manner.

For example, “That roller coaster was absolutely bonkers!”
A person might say, “I can’t believe how bonkers that party was last night.”
Another might exclaim, “You’re driving me bonkers with all your noise!”

2. Loony

Loony is a slang term derived from the word “lunatic,” which refers to a person who is mentally ill or exhibits erratic behavior. It is often used to describe someone as crazy or out of their mind.

For instance, “He’s acting like a total loony!”
A person might say, “Don’t listen to her, she’s loony.”
Another might exclaim, “I feel like I’m going loony with all the stress!”

3. Nutty

Nutty is a slang term that is used to describe something or someone as crazy, eccentric, or unpredictable. It is often used in a lighthearted or affectionate way.

For example, “That’s a nutty idea, but I love it!”
A person might say, “He’s always coming up with nutty inventions.”
Another might exclaim, “You’re driving me nutty with all your nagging!”

4. Wacko

Wacko is a slang term that is used to describe someone who is mentally unstable or behaves in an irrational or bizarre manner. It is often used in a derogatory or dismissive way.

For instance, “He’s a total wacko, don’t pay attention to him.”
A person might say, “I can’t believe the wacko things she says.”
Another might exclaim, “This whole situation is just wacko!”

5. Cuckoo

Cuckoo is a slang term that is used to describe something or someone as crazy, deranged, or mentally unstable. It is often used in a playful or affectionate manner.

For example, “You’re driving me cuckoo with your constant singing!”
A person might say, “She’s a bit cuckoo, but in a lovable way.”
Another might exclaim, “I feel like I’m going cuckoo with all this stress!”

6. Off the rocker

This phrase is used to describe someone who is acting in an irrational or unpredictable manner. It implies that the person has lost their sense of reality or sanity.

For example, “He’s completely off his rocker, talking to imaginary friends.”
In a discussion about mental health, someone might say, “People with severe schizophrenia often appear to be off their rocker.”
A friend might jokingly say, “You must be off your rocker if you think I’ll believe that story.”

7. Batty

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

For instance, “She’s a bit batty, always talking to her pet parrot.”
In a conversation about odd behavior, someone might comment, “That guy’s definitely a little batty.”
A friend might tease, “You’re acting batty today, what’s gotten into you?”

8. Cray-cray

This slang term is an abbreviation of “crazy” and is used to emphasize or exaggerate someone’s level of insanity or irrational behavior.

For example, “She went cray-cray when she found out she lost her phone.”
In a discussion about outrageous actions, someone might say, “That party last night was cray-cray, people were jumping off roofs.”
A friend might exclaim, “You’re driving me cray-cray with all your weird habits!”

9. Mad as a hatter

This phrase originates from the character of the Mad Hatter in Lewis Carroll’s “Alice’s Adventures in Wonderland.” It is used to describe someone who is mentally unstable or irrational.

For instance, “After years of exposure to toxic chemicals, he became mad as a hatter.”
In a conversation about mental health, someone might comment, “People with untreated bipolar disorder can sometimes be as mad as a hatter.”
A friend might jokingly say, “You’re mad as a hatter if you think I’ll believe that story.”

10. Out of one’s mind

This phrase is used to describe someone who is acting in a manner that is considered to be insane or irrational. It suggests that the person has lost their mental faculties or is not thinking clearly.

For example, “He’s out of his mind if he thinks he can fly without wings.”
In a discussion about bizarre beliefs, someone might say, “Flat earthers are completely out of their minds.”
A friend might tease, “You must be out of your mind to think I’ll lend you money again.”

11. Nuts

This slang term is used to describe someone or something as crazy or insane. It can be used in a lighthearted or derogatory way.

For example, “He’s completely nuts if he thinks he can jump off that cliff.”
A person might say, “I had a nuts day at work today, everything went wrong.”
Another might exclaim, “This party is nuts, there’s so much energy and excitement!”

12. Psycho

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

For instance, “She went psycho when she found out he cheated on her.”
A person might say, “I can’t believe he did that, he’s a total psycho.”
Another might warn, “Stay away from him, he’s a psycho, you never know what he might do.”

13. Loopy

This slang term is used to describe someone who is acting in a strange or eccentric manner. It can also refer to someone who is under the influence of drugs or alcohol.

For example, “He’s been acting really loopy lately, I think he’s on something.”
A person might say, “I had a loopy dream last night, it made no sense at all.”
Another might comment, “She’s always been a bit loopy, but it’s part of her charm.”

14. Barmy

This slang term is used to describe someone as mad or crazy. It is commonly used in British English.

For instance, “He’s gone completely barmy, talking to imaginary friends.”
A person might say, “Don’t mind her, she’s a bit barmy, but harmless.”
Another might exclaim, “This weather is barmy, I can’t believe it’s snowing in May!”

15. Bananas

This slang term is used to describe something as crazy, absurd, or unbelievable. It can also refer to someone who is acting in a wild or irrational manner.

For example, “The party last night was bananas, people were dancing on tables.”
A person might say, “I can’t believe she did that, she’s bananas.”
Another might comment, “This traffic is bananas, I’ve been stuck here for hours!”

16. Daft

Used to describe someone or something that is irrational or nonsensical.

For example, “He’s acting daft, talking to himself and wearing mismatched socks.”
A person might say, “That’s a daft idea. It would never work.”
In a discussion about strange behavior, someone might comment, “I saw this daft guy dancing in the rain yesterday.”

17. Meshuga

Derived from Yiddish, this term is used to describe someone who is mentally unstable or eccentric.

For instance, “She’s acting meshuga, talking to imaginary friends.”
A person might say, “Don’t mind him, he’s a bit meshuga.”
In a conversation about unusual behavior, someone might comment, “I once met a meshuga guy who believed he could talk to animals.”

18. Schizo

Short for “schizophrenic,” this term is used to describe someone who exhibits erratic or unpredictable behavior.

For example, “He’s acting schizo, switching moods every few minutes.”
A person might say, “She’s a bit schizo, you never know what she’ll do next.”
In a discussion about mental health, someone might comment, “It’s important to support those who are schizo and help them get the treatment they need.”

19. Crackpot

Used to describe someone who holds unconventional or irrational beliefs.

For instance, “He’s a crackpot, believing in conspiracy theories and alien abductions.”
A person might say, “Don’t listen to her, she’s a crackpot.”
In a conversation about strange ideas, someone might comment, “I once met a crackpot who claimed to have invented a perpetual motion machine.”

20. Demented

Used to describe someone who is mentally ill or has lost touch with reality.

For example, “He’s acting demented, laughing uncontrollably at nothing.”
A person might say, “She’s gone completely demented, talking to imaginary people.”
In a discussion about mental health, someone might comment, “It’s heartbreaking to see someone you love become demented.”

21. Unhinged

This term is used to describe someone who is mentally unstable or has lost touch with reality.

For example, “That guy’s behavior is completely unhinged.”
In a discussion about mental health, someone might say, “She was acting unhinged, so we called for help.”
A person describing a chaotic situation might say, “Everything just went unhinged after the power outage.”

22. Off one’s rocker

This phrase is used to describe someone who is acting crazy or irrational.

For instance, “He’s completely off his rocker, talking to imaginary friends.”
In a conversation about strange behavior, someone might say, “You must be off your rocker to believe that.”
A person might jokingly say, “After a long day, I feel like I’m off my rocker.”

23. Batshit crazy

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

For example, “That conspiracy theory is batshit crazy.”
In a discussion about outrageous actions, someone might say, “He went batshit crazy and started smashing things.”
A person describing a chaotic event might say, “The party last night was batshit crazy, with people dancing on tables.”

24. Off the rails

This phrase is used to describe a situation or person that has become chaotic or out of control.

For instance, “The project went off the rails when the team started arguing.”
In a conversation about someone’s behavior, someone might say, “He’s completely off the rails, doing whatever he wants.”
A person describing a party might say, “Things got off the rails when the music got louder and people started dancing on the furniture.”

25. Cracked

This term is used to describe someone who is mentally unstable or crazy.

For example, “She’s cracked, talking to herself all the time.”
In a discussion about odd behavior, someone might say, “He’s a bit cracked, but he means well.”
A person describing a tense situation might say, “Things got pretty cracked when they started arguing.”

26. Madcap

Madcap is a term used to describe someone who is wild, impulsive, or reckless in their actions or behavior.

For example, “He’s always coming up with madcap ideas that never seem to work.”
In a comedy film, a character might be described as “a madcap adventurer.”
A friend might say, “You’re such a madcap, always up for an adventure!”

27. Nutter

Nutter is a slang term used to refer to someone who is considered crazy, eccentric, or mentally unstable.

For instance, “He’s a bit of a nutter, always talking to himself.”
In a conversation about unusual hobbies, someone might say, “I met this nutter who collects rubber ducks.”
A friend might jokingly say, “You’re a nutter, but that’s why we love you!”

28. Wackadoo

Wackadoo is a playful term used to describe someone who is eccentric, odd, or a little bit crazy.

For example, “She’s a total wackadoo, always wearing mismatched socks.”
In a discussion about unique personalities, someone might say, “I work with this wackadoo who sings opera during lunch.”
A friend might affectionately say, “You’re such a wackadoo, but that’s why we’re friends!”

29. Loon

Loon is a slang term used to describe someone who is crazy, foolish, or eccentric in their behavior.

For instance, “He’s a real loon, always saying the strangest things.”
In a conversation about memorable characters, someone might say, “Have you met the loon who lives down the street?”
A friend might playfully say, “You’re such a loon, always making us laugh!”

30. Nutjob

Nutjob is a derogatory slang term used to refer to someone who is considered crazy, mentally unstable, or irrational.

For example, “He’s a complete nutjob, always coming up with conspiracy theories.”
In a discussion about unusual behaviors, someone might say, “I met this nutjob who believes they can talk to squirrels.”
A friend might jokingly say, “You’re a nutjob, but that’s why we love you!”

31. Bats in the belfry

This phrase is used to describe someone who is not mentally sound or has irrational thoughts or behaviors. It originates from the idea of bats flying around inside a church belfry, which is considered an unusual and chaotic sight.

For example, “She’s got bats in the belfry if she thinks she can fly without wings.”
A person might say, “Don’t mind him, he’s got a few bats in the belfry.”
A friend might jokingly ask, “How many bats do you have in your belfry today?”

32. Cracked in the head

This phrase is used to describe someone who is mentally unstable or crazy. It suggests that there is something wrong with the person’s mind, as if it is “cracked” or broken.

For instance, “He must be cracked in the head if he believes that conspiracy theory.”
A person might say, “I think she’s a bit cracked in the head, but she’s harmless.”
Someone might describe a bizarre behavior by saying, “That’s the kind of thing only someone cracked in the head would do.”

33. Fruit loop

This term is used to describe someone who is crazy or eccentric, often in a lighthearted or humorous way. It references the colorful and sugary cereal, suggesting that the person is “fruity” or a bit out of touch with reality.

For example, “He’s a real fruit loop with all his conspiracy theories.”
A person might say, “Don’t mind her, she’s a bit of a fruit loop.”
Someone might jokingly ask, “How many fruit loops does it take to screw in a lightbulb?”

34. Madhouse

This term is used to describe a situation or place that is chaotic, crazy, or out of control. It suggests a lack of order or sanity, as if it resembles a mental institution or “madhouse.”

For instance, “The office was a madhouse during the holiday rush.”
A person might say, “This party is a total madhouse, I can’t hear myself think.”
Someone might describe a chaotic event by saying, “It was like a madhouse in there, people were running everywhere.”

35. Looney tunes

This phrase is used to describe someone who is crazy or mentally unstable. It references the animated television show “Looney Tunes,” which features characters with exaggerated and often irrational behaviors.

For example, “He’s gone completely looney tunes with his conspiracy theories.”
A person might say, “She’s a bit looney tunes, but she’s harmless.”
Someone might describe a bizarre behavior by saying, “That’s the kind of thing only someone looney tunes would do.”

36. One sandwich short of a picnic

This phrase is used to describe someone who is not mentally stable or is lacking intelligence. It suggests that the person is missing something essential, like a sandwich, that would make them fully functional or rational.

For example, “He believes in conspiracy theories. He’s definitely one sandwich short of a picnic.”
In a discussion about someone’s eccentric behavior, one might say, “She’s a little strange, like she’s one sandwich short of a picnic.”
A person might jokingly comment, “After that stunt, I think he’s one sandwich short of a picnic.”

37. Out to lunch

This phrase is used to describe someone who is not mentally present or is behaving in a strange or irrational manner. It suggests that the person is “out to lunch” or not in touch with reality.

For instance, “He’s been acting really strange lately. It’s like he’s completely out to lunch.”
In a discussion about someone’s forgetfulness, one might say, “I asked her to bring the report, but she was out to lunch and forgot.”
A person might comment, “I can’t believe he said that. He must be out to lunch.”

38. Round the bend

This phrase is used to describe someone who is crazy or insane. It suggests that the person has gone “round the bend” or beyond the point of normalcy or reason.

For example, “She’s been acting really strange lately. I think she’s gone round the bend.”
In a discussion about someone’s irrational behavior, one might say, “He’s completely round the bend. I can’t make sense of anything he does.”
A person might comment, “I thought he was a little odd, but now I’m convinced he’s round the bend.”

39. Stark raving mad

This phrase is used to describe someone who is completely insane or crazy. It suggests that the person is not just mildly crazy, but is “stark raving mad” or completely out of control.

For instance, “The way he was screaming and running around, he looked stark raving mad.”
In a discussion about someone’s irrational behavior, one might say, “She’s gone stark raving mad. I’ve never seen anyone act like that before.”
A person might comment, “I can’t believe what I just witnessed. It was like something out of a movie. Absolutely stark raving mad.”

40. Whacko

This term is used to describe someone who is crazy or mentally unstable. It is often used in a derogatory or dismissive manner to imply that the person’s behavior or beliefs are irrational or illogical.

For example, “He’s a complete whacko. I don’t understand how anyone can take him seriously.”
In a discussion about someone’s eccentric behavior, one might say, “She’s a bit of a whacko, but she means well.”
A person might comment, “I can’t believe what he just said. He’s a total whacko.”

41. Zonkers

This term is used to describe someone or something that is extremely wild, chaotic, or insane.

For example, “The party last night was zonkers! People were dancing on tables and throwing drinks.”
A person might say, “I can’t believe how zonkers the traffic was today. It took me two hours to get to work.”
Another might exclaim, “This roller coaster is absolutely zonkers! It goes upside down and twists and turns like crazy!”

42. Bats in the attic

This phrase is used to describe someone who is acting irrationally or exhibiting signs of mental instability.

For instance, “Ever since she lost her job, she’s had bats in the attic. She’s been talking to herself and wearing mismatched clothes.”
A person might say, “I think he’s got bats in the attic. He keeps muttering to himself and scribbling on the walls.”
Another might comment, “She’s always had a few bats in the attic, but lately, it’s gotten worse. She’s been having paranoid delusions.”

43. Mad as a March hare

This expression is used to describe someone who is behaving in a completely irrational or insane manner.

For example, “He’s mad as a March hare! He’s been running around the office wearing a clown wig and singing at the top of his lungs.”
A person might say, “I don’t know what’s gotten into her, but she’s acting mad as a March hare. She’s been throwing dishes and screaming at everyone.”
Another might comment, “The politician’s proposal is as mad as a March hare. It’s completely unworkable and makes no sense.”

44. Nutcase

This term is used to describe someone who is considered to be mentally unstable, eccentric, or insane.

For instance, “Don’t listen to him, he’s a total nutcase. He believes in conspiracy theories and talks to invisible aliens.”
A person might say, “I can’t believe I dated that nutcase. He used to collect his toenail clippings and believed they had magical powers.”
Another might comment, “The guy who lives next door is a real nutcase. He’s always yelling at the squirrels and thinks they’re plotting against him.”

45. Goobered

This slang term is used to describe someone who is acting in an extremely crazy or unhinged manner.

For example, “He’s completely goobered. He’s been running down the street naked and yelling about the end of the world.”
A person might say, “I don’t know what happened to her, but she’s been goobered for weeks. She’s been hoarding food and barricading herself in her apartment.”
Another might comment, “The movie was so intense, it left me feeling goobered. I couldn’t sleep for days and kept having nightmares.”

46. Cuckoo for Cocoa Puffs

This phrase is used to describe someone who is completely insane or irrational. It originates from a popular cereal brand called Cocoa Puffs, which is known for its crazy and energetic bird mascot.

For example, “He’s cuckoo for Cocoa Puffs” means that he is completely crazy or obsessed.
In a conversation about someone’s odd behavior, one might say, “She’s acting like she’s cuckoo for Cocoa Puffs.”
Another usage could be, “I don’t know what got into him, but he went cuckoo for Cocoa Puffs and started throwing things around.”

47. Nutso

This term is a slang for someone who is crazy or mentally unstable. It is a shortened version of the word “nuts,” which is a colloquial term for someone who is insane.

For instance, “He went completely nutso and started screaming at everyone.”
In a discussion about someone’s erratic behavior, one might say, “She’s been acting really nutso lately.”
Another usage could be, “I can’t believe how nutso he went when he found out the news.”

48. Moonstruck

This term is used to describe someone who is completely infatuated or obsessed with someone or something. It refers to the idea that the person is so in love or captivated that they are “struck” by the moon’s influence.

For example, “She’s completely moonstruck by him and can’t stop talking about him.”
In a conversation about someone’s intense attraction, one might say, “I’ve never seen anyone so moonstruck before.”
Another usage could be, “He’s acting all moonstruck over that new car he just bought.”

49. Out of your mind

This phrase is used to describe someone who is completely crazy or irrational. It implies that the person’s thoughts or actions are not within the bounds of normality.

For instance, “You must be out of your mind if you think I’ll agree to that.”
In a discussion about someone’s outrageous behavior, one might say, “He’s completely out of his mind, jumping off rooftops like that.”
Another usage could be, “I thought she was out of her mind when she quit her stable job to pursue her dreams.”

50. Screw loose

This phrase is used to describe someone who is mentally unstable or crazy. It suggests that the person has a loose screw in their head, meaning that something is not right or functioning properly.

For example, “He’s got a screw loose if he thinks he can fly.”
In a conversation about someone’s strange behavior, one might say, “I think she’s got a few screws loose.”
Another usage could be, “You must have a screw loose to believe such a ridiculous conspiracy theory.”

51. Daffy

This term is used to describe someone who is acting in a strange or irrational manner. It can also refer to something that is absurd or nonsensical.

For example, “He’s gone daffy after staying up all night.”
A person might say, “That movie was so daffy, I couldn’t follow the plot.”
Another might describe a situation as, “It’s daffy that they expect us to work overtime without any extra pay.”

52. Gaga

This slang term is used to describe someone who is infatuated or obsessed with something or someone. It can also refer to a state of being mentally unstable or irrational.

For instance, “She’s gaga over that new band.”
A person might say, “I went gaga when I met my favorite celebrity.”
Another might describe their own behavior as, “I must have been gaga to think that would work.”

53. Kooky

This word is used to describe someone or something that is eccentric or peculiar in a charming or endearing way. It can also refer to something that is unconventional or out of the ordinary.

For example, “He’s got a kooky sense of humor.”
A person might say, “That dress is so kooky, I love it.”
Another might describe a character in a book as, “The author created a kooky protagonist who defies societal norms.”

54. On the nutty side

This phrase is used to describe someone or something that is exhibiting behavior that is considered strange or irrational. It can also refer to a situation that is chaotic or unpredictable.

For instance, “He’s always on the nutty side, you never know what he’ll do next.”
A person might say, “The party last night was on the nutty side, things got out of control.”
Another might describe a colleague as, “She’s a bit on the nutty side, but she’s brilliant at her job.”

55. Spaced-out

This slang term is used to describe someone who is in a state of detachment or absent-mindedness. It can also refer to someone who is under the influence of drugs or alcohol.

For example, “He seems really spaced-out, like he’s not even here.”
A person might say, “I feel so spaced-out after pulling an all-nighter.”
Another might describe their friend as, “She’s always spaced-out, I think she’s on something.”

56. Wacky

This term is used to describe something or someone that is eccentric, unusual, or unconventional. It often carries a positive connotation and is used to express amusement or surprise.

For example, “That comedian’s jokes are always so wacky!”
A person might say, “I love her wacky fashion sense.”
In a discussion about a bizarre event, someone might comment, “That was a wacky turn of events!”

57. Zany

Zany is a term used to describe something or someone who is unconventional, eccentric, or amusingly unconventional. It often refers to behavior or style that is outlandish or unpredictable.

For instance, “That comedian’s zany antics had the audience in stitches!”
A person might describe a friend as, “She has such a zany personality.”
In a discussion about a unique piece of artwork, someone might say, “I love the zany colors and patterns in this painting!”