Some super serious silliness has come to call. No need to check the peep-hole to identify these visitors - just ask! Knock-Knock. Who's there? Beagles. Beagles who? Beagles and cream cheese. Or, Knock-Knock. Who's there? Clark Kent. Clark Kent who? Clark Kent come, he's sick. And remember this classic; Knock-Knock. Who's there? Denise. Denise who? Denise is de sister of de nephew. Share the laughs with parents and friends!