bats in one's belfry, have

bats in one's belfry, have idiom
Be crazy or at least very eccentric, as in Sally thought her aunt's belief in ghosts indicated she had bats in her belfry. This term in effect likens the bat's seemingly erratic flight in the dark to ideas flying around in a person's head. [Early 1900s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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