I'm bad about welding while wearing jeans with frayed cuffs...have caught them on fire more than one time.
Also changed my carb on my '27 last year...in the process, obviously spilled gas on the intake and threw a shop towel on it to help soak it up. In the process of hooking up the new carb, I happened to notice that my alternator bracket was broken. No big deal, I can weld it right there on the car. Didn't even think twice about the gas soaked shop rag sitting on intake manifold. Whooosh....went up immediately as i screamed a Homer'esk scream. Oops.
Also,
Had a neighbor/friend who moved out of state, then decided to move back a couple of years later. While they were house hunting, we let them stay at our house for a couple of weeks. The wife and I were out in the '27, came back and were exhausted from the heat, wind, and noise (long drive), so we decided to take a nap. When I awoke, i happened to notice that the backyard was a bit smokey...figured the friend just started a fire in the fire-pit - didn't think anything of it. I walked out into living room to see him running out the door while on the phone - still didn't think anything of it - figured that maybe one of his kids was getting too close to the fire pit. Looked out into the backyard and saw it going up in flames. I ran out to see him beating the flames with towel (that was also on fire). He was on the phone with 911 hollering at me to give him my address. I gave it to him, and quickly grabbed the water house and proceeded to put the fire out. Lost 2/3's of my backyard. Still am not sure why he didn't just grab the hose in the first place.
His daughter asked him to start a fire in the fire pit, so he did...he grabbed a bottle of charcoal lighter fluid to help get it going...held it straight over the flames. Fire tracked the fluid up the stream, and caught the bottle on fire. He freaked out and threw it in the yard where it proceeded to go off like napalm....taking the yard with it. Got it stopped about a foot away from fence line. Whats annoying is that I have a 20+ foot concrete patio where the fire pit is in the dead center of it. If he just dropped the bottle there, it would have been fine - just eventually burned itself out - concrete doesn't burn too well. Instead, he threw it in our yard. At least he didn't throw it towards my house.