Knock knock. Who's there? Homer.

Homer who? Homer-ly, who could resist a classic like this? It's an *epic* pun, don't you think?

Knock knock. Who's there? Ego.

Ego who? Eggoing to let me in, or is that just a waffle excuse?

Knock knock. Who's there? Alpaca.

Alpaca who? Alpaca the suitcase if you open the door!

Knock knock. Who's there? Cows go.

Cows go who? No, cows go 'moo'.