Bats in the belfry

Meaning

Refers to someone who is acting a bit strange or eccentric. It implies that their mind is a bit cluttered or flighty, just like an old tower full of bats.

Playful, observant

Used in a sentence

• I think he has bats in the belfry the way he talks to his plants.
• She definitely has bats in the belfry if she thinks we are moving to Mars.
• My uncle has always had bats in the belfry, but we love him anyway.