Back in the early 70's, I was singing and playing bass at a rehearsal for a rock gig at a local bar when I mentioned to the guitar player that I thought the polarity was wrong on the PA. I told him I was getting little shocks through my moustache whenever I got too close to the mic. He didn't pay much attention saying I should change the polarity on my amp when I suddenly sneezed.

They later told me they could see the blue arc travelling from the mic, down the string of snot and up into my nose. All I know is my eyes rolled to the back of my head and I saw nothing but white and smelled smoke for a second. Then I was aware of the drummer falling off his throne, laughing. I sure am glad things are better grounded these days!!