Knock-Knock! Who's there? Frayed. Frayed who? Frayed no one's going to answer the door.
Did you hear about the guy who invented the knock-knock joke? He won the 'no-bell' prize.
Knock Knock Who's there? Madam Madam who?
Madam foot's caught in the door!
Knock Knock. Who's there? Anita. Anita who? Anita really warm place to sleep tonight, it's cold out here.
Knock, Knock Who's there? Cows go. Cows go who? No, silly! Cows go moo!
Knock, knock. Who's there? Dwayne Dwayne who? Dwayne the bathtub mommy, I'm dwowning.
Knock Knock? who's there? Hatch Hatch-who? Bless you.
Knock knock. Who's there? Cows. Cows who? No, owls hoo, cows moo.