"goofball" in the noun sense
1. fathead, goof, goofball, bozo, jackass, goose, cuckoo, twat, zany
a man who is a stupid incompetent fool
2. clown, buffoon, goof, goofball, merry andrew
a person who amuses others by ridiculous behavior
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License