Have Bats In One's Belfry Meaning

(idiomatic, intransitive) To be crazy or eccentric.

Example:   Anyone declaring himself Emperor of San Francisco probably had bats in his belfry.
1900, Mary Etta Stickney, Brown of Lost River, p254
  You would certainly take the prize for bats in the belfry!--flying off on a wild-goose chase across a country where even the geese need a compass to keep to the course.