The origin of knock knock jokes has been shrouded in mystery, but a potential source may have been in William Shakespeare's Macbeth in 1606. In Act 2, Scene 3, a hungover porter uses the phrase, "Knock, knock, who's there?" in his monologue. Regardless of their true origin, knock knock jokes have made it clear that they're here to stay. And every man, dad or not, is better off …Continue Reading