Cathy from Minnesota offers this joke…
Knock, knock 
Who’s there?
Turnip
Turnip, who?
Turnip the heat, it’s cold in here!
Explanation: This joke plays on words turnip/ turn up. A turnip is a vegetable; “turn up” is what you do to the heat when it is too low (you can also turn up the radio, …).
Explain the Joke 