Idiom Meaning: " To Have Bats in One's Belfry" On a metaphorical note, someone who has " Bats in the Belfry" is crazy or eccentric. This phrase is responsible for the use of "bats" for "crazy" . -Are you completely bats? and the occasional use of "belfry" for "head". -He's not quite right in the belfry. "To have bats in the Belfry" means: to be silly and slightly crazy and behave in a confused way. THESAURUS Around the bend, battle-scarred, disturbed, (as) mad as a hatter/ March hare, basket case, be besinde yourself, be losing it, be not (quite) right in the mind, be of sound/unsound mind, be off your head, be out to lunch, be/go round the twist, certifiable, deranged, dysfunctional, insanity, identity crisis, institutionalization, irra...