Ok, first let me preface that I bite my nails, and as such they're not useful for much of anything. Now, the story...
I was at a friend's house, about 3-4 years ago, stringing xmas lights. I had untangled a string that was 30 ft long or some ridiculous length. Out of the 4 strands, 1 wouldn't light, so looking down the string, (while plugged in, of course) I went lightbulb to lightbulb, testing each one. Finally I got to the bulb that was obviously the problem. The glass on it was fully broken off, so the two wires in the bulb were just sitting there, exposed. I tried to pull it out with my fingers, but it was stuck pretty good and I couldn't get it out with my lack of nails.
So I used my teeth.
Yes, the lights were still plugged in. Yes 3/4 of the lights were lit so it was blatantly obvious that they were plugged in. Yes, I recieved quite a shock to the tongue/teeth. I immediately dropped the strand and pretended nothing had happened. It was a good year before I told anyone.