WordNet (r) 3.0 (2006):

bozo
    n 1: a man who is a stupid incompetent fool [syn: fathead,
         goof, goofball, bozo, jackass, goose, cuckoo,
         twat, zany]
    2: an informal term for a youth or man; "a nice guy"; "the guy's
       only doing it for some doll" [syn: guy, cat, hombre,
       bozo]