I don't remember when exactly, but a while ago there was a thread describing someone receiving a shock through a mic. I saw this happen just a few days ago. I was running sound for a french club cabaret. The setup wasn't the greatest and i had to borrow from the theater setup. One of the acts was a live band. They had set up their equipment for a sound check, and unknown to me, the guitarist had plugged his amp into the same powerstrip as my system. As the guitarist approached the mic with his guitar, he recieved quite a shock. I had never encountered this before. After moving his amp to another circuit everything was fine. It was quite a head scratcher though.