zany

nouns

a buffoon in one of the old comedies; imitates others for ludicrous effect
zany
is a type of (narrower)
a person who amuses others by ridiculous behavior
buffoon, clown, goof, goofball, merry andrew
a man who is a stupid incompetent fool
bozo, cuckoo, fathead, goof, goofball, goose, jackass, twat, zany

adjectives

ludicrous, foolish
"gave me a cockamamie reason for not going"; "wore a goofy hat"; "a silly idea"; "some wacky plan for selling more books"
cockamamie, cockamamy, goofy, sappy, silly, wacky, whacky, zany
like a clown
"a buffoonish walk"; "a clownish face"; "a zany sense of humor"
buffoonish, clownish, clownlike, zany