Among other good jokes in a Usenet thread discussing jazz jokes:

Q. What’s the difference between a jazz musician and a large cheese pizza? A. A large cheese pizza can feed a family of four.

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A stray cat wanders into a piano bar. He proceeds to hop up on to the piano and drag his bits & pieces across the top. A patron asks the piano layer “Excuse me, do you know there’s a cat dragging his balls across the piano?”

“No,” replies the piano player, “but if you hum a few bars I can probably pick it up.”

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Q. How can you tell which kid on a playground is the child of a trombonist ?? A. He doesn’t know how to use the slide, and he can’t swing…

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Q. What has three legs and an ass on top? A. A drum stool.