50 Idioms for Crazy Person With Meanings & Sentences
Idioms for Crazy Person
1. Mad as a Hatter
Meaning: Acting very strange or crazy.
In a Sentence: The old man next door is as mad as a hatter. / Tom acted mad as a hatter after two sleepless nights.
Other Ways to Say: Bonkers, Not in their right mind
2. Off one’s rocker
Meaning: Mentally unstable or behaving irrationally.
In a Sentence: He must be off his rocker to quit his job like that.
Other Ways to Say: Nuts, Loopy
3. Out to Lunch
Meaning: Not paying attention or acting a bit odd.
In a Sentence: She was totally out to lunch during the meeting.
Other Ways to Say: Spaced out, Not all there
4. Batty
Meaning: Slightly crazy or eccentric.
In a Sentence: Grandma may seem batty, but she’s still sharp.
Other Ways to Say: Eccentric, Quirky
5. One sandwich short of a picnic
Meaning: Not very smart or a bit crazy.
In a Sentence: That guy’s one sandwich short of a picnic.
Other Ways to Say: Not all there, A few screws loose
6. A few screws loose
Meaning: Not mentally stable.
In a Sentence: That clown definitely has a few screws loose.
Other Ways to Say: Not right in the head, Unhinged
7. Loony tunes
Meaning: Very silly or mentally unstable.
In a Sentence: She started acting like loony tunes after her fifth coffee.
Other Ways to Say: Wacky, Crazy
8. Bonkers
Meaning: Completely mad or crazy.
In a Sentence: He’s bonkers to try skydiving without training.
Other Ways to Say: Nuts, Out of his mind
9. Cuckoo
Meaning: Insane or silly.
In a Sentence: You’d have to be cuckoo to wear that hat in public!
Other Ways to Say: Nutty, Loopy
10. Nutcase
Meaning: A crazy or strange person.
In a Sentence: Don’t listen to him—he’s a total nutcase.
Other Ways to Say: Psycho, Wacko
11. Not playing with a full deck
Meaning: Not completely sane.
In a Sentence: He’s not playing with a full deck if he thinks that’ll work.
Other Ways to Say: Half-baked, Unbalanced
12. Cracked
Meaning: Mentally disturbed.
In a Sentence: That painter’s genius, but he’s a little cracked.
Other Ways to Say: Unhinged, Loony
13. Around the bend
Meaning: Crazy or eccentric.
In a Sentence: She’s gone around the bend with those conspiracy theories.
Other Ways to Say: Off the rails, Mad
14. Crazy like a fox
Meaning: Seeming foolish but actually clever.
In a Sentence: He may act silly, but he’s crazy like a fox in business.
Other Ways to Say: Tricky, Sneaky smart
15. Lost one’s marbles
Meaning: Gone insane.
In a Sentence: He’s lost his marbles if he thinks that plan will work.
Other Ways to Say: Nuts, Off his rocker
16. Out of one’s mind
Meaning: Insane or behaving irrationally.
In a Sentence: You’re out of your mind to eat that hot pepper!
Other Ways to Say: Bonkers, Loopy
17. Barking mad
Meaning: Completely crazy (British slang).
In a Sentence: That idea is barking mad!
Other Ways to Say: Totally insane, Crackpot
18. Gone bananas
Meaning: Acting wild or irrationally.
In a Sentence: The fans went bananas after the win.
Other Ways to Say: Nuts, Hyper
19. Wacko
Meaning: Strange or crazy person.
In a Sentence: That guy wearing ten watches is a wacko.
Other Ways to Say: Eccentric, Weird
20. Psycho
Meaning: Dangerous or mentally unstable.
In a Sentence: He turned into a psycho over a parking spot!
Other Ways to Say: Maniac, Madman
21. Touched in the head
Meaning: Slightly insane.
In a Sentence: He’s nice but a bit touched in the head.
Other Ways to Say: Off, Odd
22. Nutty as a fruitcake
Meaning: Completely crazy.
In a Sentence: That inventor is nutty as a fruitcake.
Other Ways to Say: Mad, Wacky
23. A wild card
Meaning: Unpredictable or unusual.
In a Sentence: You never know what she’ll say—she’s a wild card.
Other Ways to Say: Unstable, Loose cannon
24. A loose cannon
Meaning: Unpredictable and possibly dangerous.
In a Sentence: He’s a loose cannon in the office.
Other Ways to Say: Wild, Reckless
25. Crackpot
Meaning: An eccentric or crazy person.
In a Sentence: He’s just a harmless old crackpot.
Other Ways to Say: Oddball, Wacko
26. Wacky
Meaning: Funny or bizarre.
In a Sentence: That wacky comedian made the whole crowd laugh.
Other Ways to Say: Zany, Goofy
27. Bizarre
Meaning: Very strange or unusual.
In a Sentence: That’s the most bizarre thing I’ve seen all week.
Other Ways to Say: Outlandish, Freaky
28. Zany
Meaning: Amusingly unconventional.
In a Sentence: His zany ideas always catch us off guard.
Other Ways to Say: Silly, Absurd
29. Eccentric
Meaning: Unconventional or slightly strange.
In a Sentence: She’s an eccentric artist who paints with ketchup.
Other Ways to Say: Quirky, Odd
30. Off the wall
Meaning: Unusual or crazy.
In a Sentence: That movie was totally off the wall!
Other Ways to Say: Outrageous, Madcap
31. Gone off the deep end
Meaning: Lost control emotionally or mentally.
In a Sentence: He went off the deep end when he lost the game.
Other Ways to Say: Snapped, Freaked out
32. Over the top
Meaning: Excessively wild or dramatic.
In a Sentence: Her costume was totally over the top!
Other Ways to Say: Too much, Extreme
33. Insane in the membrane
Meaning: Slang for being crazy.
In a Sentence: You must be insane in the membrane to try that!
Other Ways to Say: Mad, Bonkers
34. Goofy
Meaning: Silly or crazy in a funny way.
In a Sentence: He’s just being goofy—don’t mind him.
Other Ways to Say: Silly, Wacky
35. Delusional
Meaning: Holding false beliefs, often due to mental instability.
In a Sentence: He’s delusional if he thinks he can fly.
Other Ways to Say: Out of touch, Detached from reality
36. Fruit loop
Meaning: Slang for a crazy person.
In a Sentence: That guy who talks to trees is a fruit loop.
Other Ways to Say: Weirdo, Crackpot
37. Loco
Meaning: Spanish slang for crazy.
In a Sentence: You’re loco if you try that stunt.
Other Ways to Say: Mad, Nutty
38. Dazed and confused
Meaning: Acting spaced out or bewildered.
In a Sentence: He walked in dazed and confused after his nap.
Other Ways to Say: Out of it, Lost
39. Gone bonkers
Meaning: Lost one’s mind.
In a Sentence: Everyone went bonkers during the sale.
Other Ways to Say: Crazy, Insane
40. Maniac
Meaning: A wildly insane or dangerous person.
In a Sentence: He drove like a maniac through traffic.
Other Ways to Say: Lunatic, Psycho
41. Nutjob
Meaning: Informal term for a crazy person.
In a Sentence: That nutjob thinks aliens are watching us.
Other Ways to Say: Crackpot, Wacko
42. Not all there
Meaning: Mentally absent.
In a Sentence: I think he’s not all there today.
Other Ways to Say: Spaced out, Loopy
43. Off the rails
Meaning: Gone completely out of control.
In a Sentence: The conversation went off the rails quickly.
Other Ways to Say: Off track, Chaotic
44. Hysterical
Meaning: Wild or uncontrolled behavior.
In a Sentence: She was hysterical after hearing the joke.
Other Ways to Say: Laughing mad, Frenzied
45. Wild-eyed
Meaning: Looking crazed or unstable.
In a Sentence: He ran in with wild-eyed excitement.
Other Ways to Say: Frenzied, Alarmed
46. Clownish
Meaning: Acting silly like a clown.
In a Sentence: His clownish behavior got him in trouble.
Other Ways to Say: Goofy, Absurd
47. Kooky
Meaning: Strange but amusing.
In a Sentence: That’s one kooky way to decorate a house.
Other Ways to Say: Wacky, Odd
48. Absurd
Meaning: Completely ridiculous.
In a Sentence: That’s an absurd idea!
Other Ways to Say: Ridiculous, Nonsensical
49. Loon
Meaning: Informal word for a crazy person.
In a Sentence: That loon danced in the rain for hours.
Other Ways to Say: Nutcase, Madman
50. The lights are on but nobody’s home
Meaning: Appearing alert but mentally absent.
In a Sentence: He just stared blankly—the lights were on but nobody’s home.
Other Ways to Say: Zoned out, Not all there
