And others that I have heard, stolen, etc.:
Q: How do you know when a violist is at your door?
A: He can't find the key and doesn't know when to come in.
Q: What's the definition of perfect pitch?
A: Chucking a viola at the toilet without hitting the rim.
Q: What's the range of a viola?
A: 25 feet, if you kick it hard enough.
Q: How do you get a violist to play a staccato 32nd note?
A: Write a whole note, underneath it write ff espressivo. Or solo.
Q: How do you get a cellist to play a loud whole note?
A: Write a 32nd note, and underneath it, pp espressivo.
Small wonder there's such a problem with air pollution when so much of it has passed through saxophones.
Q: What's the difference between a horn player and a seamstress?
A: The seamstress tucks up the frills...
Q: What's the difference between an orchestra and a bull?
A: The bull has the horns in the front and the asshole in the back.
Q: What's the difference between a soprano and a pirahna?
A: Lipstick