I installed a water heater just before Christmas for one of my repeat customers. There was a leak just inside the wall to the right side of the water heater, and I told the people I would fix it as part of the job. When I got to that part, I shoved the insulation out of the way and up into the stud bay. The paper backing on the insulation lit up while I was soldering the new parts in. It's happened before and it usually goes out pretty quickly by itself or just blowing it out. Not this time.
I kept seeing a glow coming from inside the wall and it didn't look like it was going to go out by itself. I panicked a bit and reached up inside the wall and snatched the insulation out and stomped it out on the floor. While doing my little highland jig in the utility room, my torch rotated in my hand and set my shirtsleeve on fire. Brand new shirt. The insulation was from the sixties, I think, and the fiberglass was stuck on to the paper with a black tar. When I grabbed the insulation up in the wall the burning tar stuck to my fingertips on my left hand and burned the heck out of them.
Other than that, the job went beautifully. No witnesses, thank God.