nuttier than a fruitcake
Crazy or wacky. Usually used humorously. The kids are always nuttier than fruitcakes when they've had something sugary to eat. My Aunt Jeannie has always been nuttier than a fruitcake.
nuttier than a fruitcake
Crazy, eccentric. This term originated in America about 1920 and transfers the actual nuts in a fruitcake to the colloquial meaning of nutty as crazy. The term later gave rise to the usage fruitcake for an eccentric individual.