Dr. Knucklehead is knock-knocking at the door and children will happily answer, because they love knock-knocks--and these are the very best. Try this: Knock Knock . Who's there? Daisies . Daisies who? Days he's a man, but by night, he's a werewolf! Or laugh a lot at this: Knock Knock . Who's there? Billows . Billows who? Bill owes me ten bucks and he said you'd give it to me . Every one is riotously funny.