Knock knock. Who's there? The door.

The door who? The door you just knocked on. It's not a person, it doesn't have a name.

Knock knock. Who's there? Alpaca.

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

Knock knock. Who's there? Marmalade.

Marmalade who? Ma'am, I'd like to spread some cheer with a joke that's jam-packed with puns!

Knock knock. Who's there? Nimbus.

Nimbus who? Nimbus sure I'm at the right door, the forecast said I'd find you here!