Knock knock. Who's there? Fig.

Fig who? Fig-ure it out yourself, I'm busy!

Knock knock. Who's there? Silence.

Knock knock. Who's there? A door.

A door who? A door has no 'who,' it's an inanimate object.

Knock knock. Who's there? Peas.

Peas who? Peas-fully waiting for you to open the door!