Knock knock. Who's there? You tell me.

You tell me who? No, *you* tell *me* who's there. I'm the one knocking, how should I know who's inside?

Knock knock. Who's there? That's what I'm asking.

That's what I'm asking who? That's what I'm asking who wants to know who's on the other side of this door!

Knock knock. Who's there? Parenthesis.

Knock knock. Who's there? Next.

Next who? Next time, just open the door, this isn't a surprise party.