have a screw loose

Idioms  

1. Be mentally unstable or eccentric, as in Anyone who approves that purchase must have a screw loose. This term likens a mental weakness to a machine in which a part is not securely fastened. An antonym is have one's head screwed on right; for example, She's very capable; she has her head screwed on right. [Slang; early 1800s]

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Example Sentences

See Examples For:

have a screw loose

“Everyone in speedskating recognizes that Eric Heiden is the greatest speedskater who ever lived. Even saying, ‘Yeah, we should try that,’ that’s like saying, ‘Do you have a screw loose or something?’

From Washington Times ● Mar. 8, 2023

“But you have to have a screw loose to play this position.”

From New York Times ● Nov. 24, 2011

Those that think scrapping everything kind of have a screw loose.

From Forbes ● Oct. 14, 2011

But one Sebring dictum must be strictly observed: "Oil is for machinery and moving parts; unless you have a screw loose, it has no place on the head."

From Time Magazine Archive

I really and truly believe he must have a screw loose in the upper story.”

From The Big Five Motorcycle Boys on the Battle Line Or, With the Allies in France by Ralph Marlow