We had a hot sauce in college called Da Bomb IIRC. It was the stupid hot variety best used for dares and gags.
We were all hanging out one afternoon when my buddy came home w/ it and brought out a few tooth picks for us all to sample it. He told us not to touch it with our fingers or unscrew the cap without a tissue or some barrier between our skin. It gave me hiccups for 1/2 hour.
Anyhow, our buddy Mike didn't believe us and dipped his entire finger in the sauce and tested it. It obviously made him miserable for the next hour or so. But the best part was a day later as I walked into their apartment, he was in the kitchen with his di*k in a bowl of milk. Evidently, when he went to the bathroom later that day and touched his junk, it burned pretty bad.
Mike wasn't the best listener.