A form of an insult,
usually meaning 'crazy'.
Or, a kind of dessert that deeply resembles a
loaf of bread only it's a lot sweeter, softer, and contains candied fruit... Which aren't
actually fruits at all.
1) A person digs through trash and eats it.
Observer says, "Dude, what a fruit cake!"
2) Why a 'fruit cake' is called a fruit cake is a mystery since
it isn't really a cake, and
it doesn't even have fruits inside.