Knock knock. Who's there? Dictionary.

Dictionary who? I'm not defining the terms of this conversation.

Knock knock. Who's there? Wheat

Wheat who? Wheat you waiting for, let me in

Knock knock. Who's there? A pause.

A pause who? No, just a pause. The joke's over.

Knock knock. Who's there? Ivan.

Ivan who? Ivan telling you to open this door for ages, my knuckles are practically knocking themselves!