Knock knock. Who's there? Alpaca.

Alpaca who? Alpaca the bags, we're going on vacation!

Knock knock. Who's there? Silence.

Knock knock. Who's there? Nobody.

Nobody who? Exactly. Why are you talking to the door?

Knock knock. Who's there? That's what I'm asking.

That's what I'm asking who? That's what I'm asking who wants to know who's on the other side of this door!