Here's one Mark Kermode told (he's a double bass player, just to be clear).
The band is having a practice session and they break for lunch. The vocalist, keyboard player and lead guitarist go out for lunch. When they get back, they find the bass player beating the crap out of the drummer. "What are you doing?" says the guitarist.
"The drummer put one of my strings out of tune", says the bass player who then beats on the drummer some more.
"That's no reason to beat him up", says the guitarist.
"Yes, but he won't tell me which one."