Language is more than just words; it’s about creativity, expression, and culture. One of the most colorful aspects of English is idioms—phrases that don’t always mean what they literally say but carry figurative meanings.
Idioms help us capture emotions, describe situations vividly, and even add humor to conversations. When it comes to describing a crazy person, English is packed with funny, witty, and sometimes quirky idioms that reflect how people talk about unusual or eccentric behavior.
Using idioms for “crazy person” makes conversations lively. Instead of just saying someone is “weird” or “mad,” you can use expressions like off one’s rocker or a few screws loose.
These idioms add color and personality to your speech or writing. Whether you want to sound playful, humorous, or dramatic, idioms are your best tool. Let’s explore some of the most interesting ones!
Did You Know?
The English language has over 25,000 idiomatic expressions, and many of them are related to madness or eccentricity. Why? Because throughout history, mental strangeness has fascinated people and inspired colorful language. From Shakespeare’s plays to modern comedy shows, idioms about “crazy” behavior have been a constant source of creativity.
Idioms for Crazy Person
To make things easier, here are idioms grouped into four main themes:
- Mechanical & Object-Based Idioms (comparing madness to broken machines).
- Animal & Nature-Based Idioms (using creatures or nature to describe eccentricity).
- Behavior & Personality Idioms (based on how people act).
- Playful & Humorous Idioms (funny ways to call someone “crazy”).
Mechanical & Object-Based Idioms
A few screws loose
Meaning: Someone who behaves strangely or irrationally.
Example: “I think he has a few screws loose—he just tried to talk to his cat about politics!”
Alternative: Not playing with a full deck.
Reflection: Common in informal speech, often playful but can sound insulting if serious.
Not playing with a full deck
Meaning: Someone who is not completely sane.
Example: “She believes her dog can text her. She’s not playing with a full deck.”
Alternative: One card short of a deck.
Reflection: Light-hearted, used mostly in casual conversations.
Off one’s rocker
Meaning: Acting in a very strange or mad way.
Example: “When he suggested climbing Everest without training, I thought he was off his rocker.”
Alternative: Out to lunch.
Reflection: Old-fashioned but still popular, often used in humorous contexts.
One brick short of a load
Meaning: Someone who isn’t very smart or rational.
Example: “That guy’s one brick short of a load—he wears sunglasses at night.”
Alternative: A sandwich short of a picnic.
Reflection: Informal, often used jokingly.
A screw loose
Meaning: A simpler version of “a few screws loose,” meaning mentally unstable.
Example: “He must have a screw loose if he thinks that idea will work.”
Alternative: Nuts.
Reflection: Short and punchy; used casually.
The lights are on but nobody’s home
Meaning: Someone seems present physically but absent mentally.
Example: “She stared at me blankly—the lights were on, but nobody’s home.”
Alternative: Empty upstairs.
Reflection: Humorous, used for forgetful or distracted people.
Not all there
Meaning: Mentally unstable or eccentric.
Example: “I don’t trust him; he’s not all there.”
Alternative: Lost his marbles.
Reflection: Informal, sometimes considered rude.
A few cards short of a full deck
Meaning: Lacking intelligence or sanity.
Example: “He’s a few cards short of a full deck—look at the way he dresses in the snow!”
Alternative: A few fries short of a Happy Meal.
Reflection: Funny and playful, good for casual jokes.
Out to lunch
Meaning: Completely distracted or crazy.
Example: “She forgot her own birthday—she’s out to lunch.”
Alternative: Spaced out.
Reflection: Used in casual, light humor.
Not firing on all cylinders
Meaning: Someone isn’t thinking properly.
Example: “You’re not firing on all cylinders today—take a break.”
Alternative: Running on empty.
Reflection: Common in workplaces or daily chats.
Animal & Nature-Based Idioms
Mad as a hatter
Meaning: Completely crazy.
Example: “He runs around singing in the rain—mad as a hatter.”
Alternative: Batty.
Reflection: Originates from 19th-century hat makers; widely used.
Batty
Meaning: Slightly mad or eccentric.
Example: “My neighbor is batty—she decorates her yard with 50 pink flamingos.”
Alternative: Nuts.
Reflection: Informal, often playful.
Crazy like a fox
Meaning: Appears crazy but is actually clever.
Example: “He acts silly, but he’s crazy like a fox—he always gets the deal.”
Alternative: Smart fool.
Reflection: Used positively, showing cleverness.
Gone to the dogs
Meaning: Lost control or sanity.
Example: “Since the manager left, the company’s gone to the dogs.”
Alternative: In shambles.
Reflection: Can be about people or situations.
Mad dog
Meaning: Someone dangerously crazy.
Example: “He fought like a mad dog.”
Alternative: Rabid.
Reflection: More aggressive; less playful.
Wild goose chase
Meaning: A crazy, pointless pursuit.
Example: “Looking for his phone in the desert was a wild goose chase.”
Alternative: Fool’s errand.
Reflection: Often about senseless activities.
Barking mad
Meaning: Extremely mad or foolish.
Example: “She’s barking mad if she thinks that plan will work.”
Alternative: Nuts.
Reflection: British English, often humorous.
Loony bird
Meaning: A silly or crazy person.
Example: “He’s a real loony bird with his odd inventions.”
Alternative: Oddball.
Reflection: Light, playful insult.
Monkey business
Meaning: Foolish or crazy behavior.
Example: “Stop this monkey business and get serious.”
Alternative: Horseplay.
Reflection: Common with children or informal settings.
Behavior & Personality Idioms
Lost his marbles
Meaning: Gone mad or lost sanity.
Example: “He thinks aliens control traffic lights—he’s lost his marbles.”
Alternative: Nuts.
Reflection: Very common in casual speech.
Out of one’s mind
Meaning: Extremely irrational or crazy.
Example: “He must be out of his mind to quit without another job.”
Alternative: Insane.
Reflection: Neutral tone, used both seriously and playfully.
Nutcase
Meaning: A crazy person.
Example: “That guy yelling at pigeons is a nutcase.”
Alternative: Loony.
Reflection: Casual, often a bit rude.
Cracked
Meaning: Not mentally stable.
Example: “He’s cracked if he thinks he can eat 20 burgers.”
Alternative: Bonkers.
Reflection: Used in informal settings.
Bonkers
Meaning: Crazy or mad.
Example: “She’s bonkers for spending that much on shoes.”
Alternative: Nuts.
Reflection: British English, fun and informal.
Berserk
Meaning: Out of control, crazy with anger.
Example: “He went berserk when he lost the game.”
Alternative: Frenzied.
Reflection: More intense than playful.
Wacky
Meaning: Amusingly strange or crazy.
Example: “She wears wacky outfits to every party.”
Alternative: Zany.
Reflection: Friendly, non-insulting.
Zany
Meaning: Funny but crazy behavior.
Example: “The comedian is zany but hilarious.”
Alternative: Wacky.
Reflection: Light, humorous, not offensive.
Eccentric
Meaning: Strange but interesting behavior.
Example: “He’s eccentric, always collecting old radios.”
Alternative: Quirky.
Reflection: Less insulting, sometimes positive.
Oddball
Meaning: A strange or unusual person.
Example: “He’s a bit of an oddball, but we like him.”
Alternative: Weirdo.
Reflection: Neutral, not always negative.
Playful & Humorous Idioms
A nut job
Meaning: A crazy person.
Example: “He’s a real nut job for climbing that tree at midnight.”
Alternative: Nutcase.
Reflection: Informal, humorous insult.
Fruitcake
Meaning: Someone who’s completely crazy.
Example: “Only a fruitcake would wear pajamas to a wedding.”
Alternative: Loony.
Reflection: Informal, playful.
Barmy
Meaning: Silly or crazy.
Example: “You’re barmy if you think that will work.”
Alternative: Bonkers.
Reflection: British, casual, humorous.
Loony tunes
Meaning: A very crazy person.
Example: “He’s loony tunes—always talking to himself.”
Alternative: Nuts.
Reflection: Inspired by cartoons, very informal.
Nutty as a fruitcake
Meaning: Completely crazy.
Example: “She’s nutty as a fruitcake, collecting 1,000 rubber ducks.”
Alternative: Bonkers.
Reflection: Humorous and playful.
Dippy
Meaning: Silly and slightly crazy.
Example: “She can be a bit dippy sometimes, but she’s sweet.”
Alternative: Ditzy.
Reflection: Informal, often used about women.
Touched in the head
Meaning: Not completely sane.
Example: “He’s touched in the head if he thinks that’s possible.”
Alternative: Not all there.
Reflection: Informal, sometimes harsh.
Screwball
Meaning: A strange or crazy person.
Example: “He’s a screwball, but he’s funny.”
Alternative: Oddball.
Reflection: Used often for comic characters.
Crazy as a loon
Meaning: Totally crazy.
Example: “That guy’s crazy as a loon—he swims in freezing water.”
Alternative: Mad as a hatter.
Reflection: Informal, playful insult.
Off the wall
Meaning: Very unusual or crazy ideas.
Example: “That’s an off-the-wall plan, but it might work.”
Alternative: Outlandish.
Reflection: Often used for creativity or silliness.
How to Use These Idioms in Daily Life
Idioms for “crazy person” are mostly used in informal conversations. Here are a few ways to use them:
- Speaking: Use playful idioms like bonkers or nutty as a fruitcake when joking with friends.
- Writing: In stories, blogs, or creative writing, idioms like off the wall add humor and personality.
- Professional settings: Be careful—avoid offensive ones. Instead, use lighter terms like eccentric or wacky.
Common Mistakes Learners Make With Idioms
- Wrong context:
❌ “My boss is barking mad in his report.”
✅ “My boss is barking mad when he gets angry.” - Literal usage:
❌ “He lost his marbles at home.”
✅ “He lost his marbles when he quit suddenly.” - Mixing idioms incorrectly:
❌ “He’s a few screws out to lunch.”
✅ “He has a few screws loose.” OR “He’s out to lunch.”
FAQs
1. Are idioms for “crazy person” offensive?
Some can be offensive if used seriously, but many are playful and humorous. Context and tone matter.
2. Can I use these idioms in business English?
Most are informal, so avoid them in formal writing. Safer options include “eccentric” or “unconventional.”
3. What’s the difference between “bonkers” and “eccentric”?
Bonkers is playful slang for “crazy,” while eccentric often means strange but interesting.
4. Are these idioms common in British and American English?
Yes, though some differ. For example, barmy and bonkers are more British, while nut job and loony tunes are common in American English.
5. Can idioms about craziness also mean creativity?
Yes! Idioms like off the wall or crazy like a fox can suggest unusual but clever ideas.
Conclusion
Idioms for “crazy person” show how playful, rich, and creative English can be. From mad as a hatter to out to lunch, these expressions bring humor, exaggeration, and color into conversations.
While many are light-hearted, always be mindful of the situation and your audience. Next time you want to describe eccentric behavior, skip plain words like “weird” or “strange” and try one of these lively idioms instead.
They’ll not only make you sound more fluent but also more fun to talk to!
