Knock knock. Who's there? Cows go.

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

Knock knock. Who's there? Hearse.

Hearse who? Hearse a real groaner for ya: I used to be a baker, but I couldn't make enough dough to roll with the big timers!

Knock knock. Who's there? Silence.

Knock knock. Who's there? This is a knock-knock joke.

This is a knock-knock joke who? Just trying to figure out where we go from here.