Knock, knock. Who's there? Nobel. Nobel who? No bell, I knock.
Knock knock! Who's there? Yah! Yah who? Naaah, bro, I prefer google.
Knock,Knock, Who is there? Pen! Pen who? is...
Knock, knock! Who's there? Spell. Spell who? W-H-O.
Knock knock. Who's there? Urine. Urine who? Urine trouble if you don't open the door.
Knock knock. Who's there? Allahu Akbar. Allahu AK- BOOM!!!
Knock Knock. Who's there? Opportunity. Don't be silly - opportunity doesn't knock twice!
Knock Knock. Who's there! Ice cream! Ice cream who? Ice cream if you don't let me in!
Knock Knock! Who's there? Justin Justin who? Justin time for dinner!
Knock, Knock! Who's there? Doctor Doctor who? That's a great TV show, isn't it?