Literally, What's up, Fool. Used instead of "Good afternoon, How are you today, Sir." or "Greetings my friend, How are you? Can also be used to taunt, such as, you're not so tough, you are sort of a fool.
Tyson to Trevor Burbick "Supfoo?" after knocking him down for the third time.
by Zipponutty September 29, 2006