Fruit cake
Someone that is crazy, spontaneous, mad, eccentric and perhaps mentally ill.
*ring ring, ring ring*
Caller: Hello is that Alex?
Unknown: No its the Psychiatric ward.
Caller: Oh whats happened to Alex.
Nurse: He was pursued by police after stealing a bottle of Vodka, downing it, getting naked and swimming in a lake. When they first attempted to arrest him he ripped a piece of wood from a fence and hit the policeman with it, so they put him in a riot van and took him here.
Caller: Hahaha oh no what an absolute fruit cake, whats the address of the ward I will come and see him.