Knock knock.
Who's there?
Wendy.
Wendy who?
Wendy wind blows de cradle will rock.
Knock knock.
Who's there?
Anita.
Anita who?
Anita borrow a pencil.
One I like to call the Bachelor Party knock-knock:
Knock knock.
Who's there?
Renato.
Renato who?
Renato gas last night.
Knock knock.
Who's there?
Ears.
Ears who?
Ears one more knock-knock joke for you.
Knock knock.
Who's there?
Ya!
Ya who?
Ride 'em cowboy!!!
All jokes courtesy knock-knock-joke.com, which urges you, "Don't knock-knock 'em till you tried 'em!"
Which isn't quite correct, grammatically, but eh. It's teh Internets.
