Knock knock. Who's there? Cows go.

Cows go who? No, cows go 'moo'.

Knock knock. Who's there? Dave.

Dave who? I don't know, *you're* the one who's supposed to open the door.

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!

Knock knock. Who's there? Cows go

Cows go who? No, cows go 'moo'