yep..been there ..last time it happened there was a bassist from another city that brought his bass and an autoharp..i was more than willing to sit out and let him play ,but he didnt even unpack it or try to play...i used to play electric at a friends jam (rock) ,and he would hand me the bass when jam time came, and he would go to the bar and leave me up there the whole set ..i appreciated it ,but it was kinda his gig not mine