clown

cutup, madcap

fool, jester, motley, scaramouch (or scaramouche)

mime, mimic, mummer, pantaloon

comedian, comedienne, comic, droll, farceur, funnyman, gagman, gagster, humorist, joker, jokester, merry-andrew, second banana, stand-up, top banana, wag, wit

barbarian, brute, caveman, Neanderthal, savage

loudmouth, vulgarian

lowlife, miscreant, rascal, rogue, roughneck, scab, scamp, scoundrel, villain, wretch

booby, fool, nincompoop, ninny, nitwit, nut

airhead, birdbrain, blockhead, dolt, dope, dork [slang], goon, half-wit, idiot, imbecile, moron, turkey