Knock knock. Who's there? Uriah.

Uriah who? Uriah-lly didn't see that pun coming, did you?

Knock knock. Who's there? Oblivion.

Oblivion who? *everything ceases to exist*

Knock knock. Who's there? Donut.

Donut who? Donut ask, just open the door!

Knock knock. Who's there? Recursion.

Recursion who? Recursion who? Knock knock.