I play drums and sometimes do jobs where other drummers will sit in on my kit. One night at a quiet Jazz gig, this jackass sat in and played super loud, repositioned the drums and Beat on them, denting the drum heads badly!! Rock Blocking!!!! I played with a pop band at SXSW at the Apple store in 08. We didn't have a bass played so the Crazy band leader said I shouldn't play because it would be hard for the band even though they had drums set up already, sounded like an excuse not to pay me for the show too!!!! Rock Blocking by your own band mates!!! I have played shows where someone had pissed off the sound guy and he decided to make it impossible to hear ourselves on stage. He also made us sound like shit!! Rock Blocking!!!