Knock knock. Who's there? Figment.

Figment who? Figment of your imagination, but I'm real and I need to come in!

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? It's me.

It's me who? It's me, and I'm not here for a joke. I actually need to borrow a cup of sugar.

Knock knock. Who's there? Wu

Wu who? Wu don't know, it's a Chinese puzzle to me, but I'm paws-itive I'll figure it out, fur-get about it!