Bats in the belfry Traditional Cache

Bats in the Belfry

"Bats in the belfry" is an idiom meaning someone is mentally unsound, eccentric, or crazy. It likens erratic bats flying around a church's belfry to crazy or nonsensical ideas rattling around in a person's head. The expression, which originated in the late 19th century, is now considered a somewhat old-fashioned phrase for being a bit nutty or mad.