Knock knock. Who's there? Alpaca.

Alpaca who? Alpaca the suitcase, you load the car!

Knock knock. Who's there? Purpose.

Purpose who? That's what I've been asking myself for years.

Knock knock. Who's there? No one.

No one who? Exactly.

Knock knock. Who's there? Taco.

Taco who? Taco 'bout a great day to see you!