Speaking of letting the smoke out :

I worked in a radio shop when I was taking electronics courses back when I was a youngster, and one day I was working on something and got a test lead across the MAIN input and it vaporized the lead tip and I had my head stuck right up in there trying to look in the case. WELP, when it arched, I gasped and sucked in that lead (now in a gaseous form) and that like to have choked my ass to death. That was one more nasty hit.