Prime8's definitions

Fruitcake

Fruitcakes, which are cakes containing both fruit and nuts, have been in existence since the Middle Ages, but it is unclear when the term started being used disparagingly, especially in the United Kingdom and the United States, as a slur for a 'crazy person' (e.g. "he's a complete fruitcake")

He's a complete fruitcake

by Prime8 August 11, 2015