leafblower joke 

1. A specific type of joke where the punch line is completely unrelated to the preceding set-up; commonly met with dead silence, although a masterful joke may elicit laughs due to sheer stupidity.

2. A version of an anti-joke that depends upon a stupid punch line instead of a logical one.

Origin: The name of this joke came about as a result of when a drug-user forgot the punch line to a joke, and simply ended it with "leafblower".

Dude 1: "Hey, what was the punch line to that leafblower joke you told me earlier about that cactus?"

Dude 2: "Oh, that one. I think it was something about a styrofoam cup."

leafblower joke by Zachariahsmith April 4, 2011