Knock knock. Who's there? Canoe.

Canoe who? Canoe let me in, it's freezing out here!

Knock knock. Who's there? The.

The who? The door, silly! You just opened it.

Knock knock. Who's there? Cows go

Cows go who? No, cows go 'moo'

Knock knock. Who's there? A man with a

manuscript for a knock-knock joke, but he's struggling to come up with a decent punchline, and honestly, it's just getting a bit meta at this point.