A few times only. One of (but not the dumbest thing) I've done was when I was in the Army, and we were at the National Training Center at Fort Irwin, a vast desert training post near Death Valley. I had to haul my 5-ton truck's battery up a long hill to the maintenance section, and rested the battery against my lap as I slogged up the hill, as the battery was a really heavy sucker.
I went back to the truck and took a nap in the cab. When I work up, I looked down and the lap down mid thiegh and part of the blouse of the jungle fatiques I was wearing had completely dissolved. It took me a few minutes to figure out what had happend.