lost their marbles

USAGE SUMMARY

The phrase "lost their marbles" is correct and usable in written English. You can use it to describe someone who is acting irrationally or has become mentally unstable. Example: After the unexpected news, he really lost his marbles and started shouting. Alternative expressions include "gone off the deep end" and "lost their mind."

✓ Grammatically correct

News & Media

Social Media

Wiki

Human-verified examples from authoritative sources

Exact Expressions

17 human-written examples

Have they lost their marbles?

Independent

"I thought they had lost their marbles".

The New Yorker

Christ have some people lost their marbles?

Independent

First they lost their marbles and then they lost their heads.

The Guardian - Film

I think the one thing they have got in common is they have both lost their marbles".

The Guardian

Once proud to be the natural party of government, they have not only lost their marbles but they are throwing them at each other.

The Guardian - Opinion

Human-verified similar examples from authoritative sources

Similar Expressions

43 human-written examples

When former George W. Bush speechwriter David Frum writes article describing how they lost their marbles-with lockstep opposition policy-he gets fired from position at conservative American Enterprise Institute.

Huffington Post

It's not like the guys are losing their marbles or anything, but we have some undisciplined times".

The New York Times - Sports

"The women in my family live to be 90 and they don't lose their marbles till 89," Chase-Brand told reporters at the time.

The New York Times - Sports

Now that they are under siege, it is no time for them to act as if they're losing their marbles.

The New York Times

But they had regularly been losing their marbles during conference week, usually about Maggie or Europe, much as Old Labour once did over The Bomb.

The Guardian - Opinion

Expert writing Tips

Best practice

Ensure the possessive pronoun matches the subject. For example, use "lost his marbles" for a singular male subject and "lost its marbles" for an organization or group acting as a single entity.

Common error

Avoid using this phrase when discussing actual diagnosed mental health conditions in a serious or professional setting. Because "lost their marbles" is inherently lighthearted and metaphorical, it can come across as dismissive or stigmatizing if used to describe genuine psychological suffering or medical emergencies.

Linguistic Context

The phrase "lost their marbles" functions as an idiomatic verb phrase. According to Ludwig AI, it is used to describe a person who has become mentally unstable or is acting in a highly irrational manner. It follows the standard verb-object-possessive structure found in many English idioms.

Expression frequency: Common

Frequent in

News & Media

75%

Social Media

15%

Wiki

5%

Less common in

Formal & Business

3%

Science

1%

Reference

1%

Ludwig's WRAP-UP

The idiom "lost their marbles" is a well-established and expressive part of the English language. Data from Ludwig shows that it is frequently employed by professional writers at The New York Times and The Guardian to critique irrational decisions or behavior in a colorful, engaging way. While it is grammatically correct and widely understood, it is best suited for informal or journalistic registers. Writers should be mindful of its playful tone and avoid using it in sensitive medical or formal business contexts where more precise or respectful language is required. Overall, it remains a powerful tool for adding personality to your prose when describing logic gone awry.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

lost their mind

Provides a slightly more direct and slightly less playful alternative while maintaining the same core meaning.

gone off the deep end

Suggests a more dramatic or sudden shift into irrational behavior or emotional instability.

gone mad

Uses more traditional, slightly dated terminology that can feel more intense depending on the context.

cracked up

Often implies a mental breakdown caused by stress or pressure rather than just general eccentricity.

gone bananas

A more lighthearted and informal way to describe someone acting wildly or irrationally.

lost their grip

Focuses on the loss of control or contact with reality rather than just the state of being 'crazy'.

flipped their lid

A slangier alternative that emphasizes a sudden loss of temper or sanity.

gone bonkers

Very informal and British-influenced slang for acting in a silly or irrational manner.

lost their sanity

A formal and clinical way to describe the same phenomenon, suitable for serious writing.

gone insane

The most literal and clinical description, carrying significantly more weight and seriousness.

FAQs

How to use "lost their marbles" in a sentence?

You can use it to describe someone acting crazy or irrational, such as: "After seeing the prices at the new restaurant, I thought the owners had "lost their marbles".

What can I say instead of "lost their marbles"?

You can use alternatives like "<a href="/s/lost+their+mind" target="_blank" rel="alternative">lost their mind", "<a href="/s/gone+off+the+deep+end" target="_blank" rel="alternative">gone off the deep end", or "<a href="/s/gone+bonkers" target="_blank" rel="alternative">gone bonkers" depending on how informal you want to be.

Is "lost their marbles" considered rude?

It is an informal idiom that is often used jokingly. While it is not a swear word, it can be seen as insensitive if used to describe a serious mental health issue rather than just a moment of poor judgment.

What is the difference between "lost their marbles" and "lost their mind"?

While both mean to become irrational, "lost their marbles" is more playful and metaphorical, whereas "<a href="/s/lost+their+mind" target="_blank" rel="alternative">lost their mind" is more direct and can be used in slightly more serious contexts.