A Grape joke is a specific type of question - answer joke. The listener is not expected to provide the answer, but to ask for it to be provided by the teller of the joke.

• A question: "What's purple and ..."
• An answer: "... grape ..."

Examples:

Q: What's purple and commutes?
A: An abelian grape.

Believed to be unique among the grape jokes, this may actually require explanation unless the listener has had a bit of exposure to college level mathematics. As it requires specialized knowledge, it is also a kind of in joke.

This joke is a word play on a mathematical term, the abelian group. One of the mathematical properties of abelian groups is their commutative property, where a*b = b*a. The setup relies on the listener assuming the more common meaning of commute - to travel from home to workplace or vice versa. (Since "home" and "workplace" may be exchanged in this description, it is in a sense also commutative.)

Q: What's purple and goes up and down?
A: A grape in an elevator.

Q: What's purple and flies?
A: Super-Grape!

Q: What's purple and vies for world domination?
A: Alexander the Grape.

See Also

• Knock-knock joke