Many years ago I was idling at a maintenance hangar and a mechanic was working on a Cessna 310 fuel drain with a lit cigarette in his mouth. He stuck his screwdriver into the drain and whatever he did caused the fuel - avgas- to come gushing out. So he calmly dropped the cigarette into the avgas on the ground and it extinguished. This was at an ambient temperature of beach clothing magnitude. No BS, I saw it with my own eyes.