There will be a half-formed joke. It is your job to complete the joke above you, and give lead to a new joke. For instance, pretend there are users One, Two, and Three.
One: "Why did the chicken cross the road?"
Two: "It wanted to lead a protest at the McDonald's across the street to stop making chicken McNuggets." "Knock knock, who's there? Orange. Orange who?"
Three: "Oranges can't knock on doors and talk, your life is a lie." "How many gophers does it take to screw in a light bulb?"
The jokes can be sarcastic, or they can be actual jokes, your call.

That's how it works. So, I will start it off.
Knock knock, who's there? Lettuce. Lettuce who?