has bats in her belfry

The idiom, has bats in her belfry, is another way of saying someone acts in a crazy and eccentric way. If you have ever imagined bats in a belfry, they would be acting somewhat crazy and out of sorts to say the least. Figuratively, the phrase is referring to a person who seems to act different than others, unique and eccentric in a way that is not common of other people they come across.