berk(British), charlie(also charley, British), cuckoo, ding-a-ling, ding-dong, dingbat, dipstick, doofus(slang), featherhead, fool, git(British), goose, half-wit, jackass, lunatic, mooncalf, nincompoop, ninny, ninnyhammer, nit(chiefly British), nitwit, nut, nutcase, simp, simpleton, turkey, yo-yo

daredevilmadman, madwomanairhead, birdbrain, blockhead, dodo, dolt, donkey, dope, dork(slang), dumbbell, dummy, dunce, fathead, gander, goon, idiot, ignoramus, imbecile, know-nothing, knucklehead, moron, numskull(or numbskull), pinhead, schlub(also shlub, slang), schlump(slang), schnook(slang), stockfeatherbrain, scatterbrainbutt, dupe, laughingstock, mockery, monkeychump, loser, schlemiel(also shlemiel)character, codger, crackbrain, crackpot, crank, kook, oddball, screwball, weirdo