So... I crashed my EF 91" Extra a few months ago, and was out picking up all the pieces to bring them back to the pit area. The plane was in splinters, so I was just stuffing things in my pockets, in what was left of the fuse, etc..
All of a sudden, one of the guys said "hey Mike, your pocket is smoking"... I jumped up, grabbed everything in the pocket and threw it out on the ground. I had an A123 battery in there, and the wires coming out of it had stripped the insulation off during the crash. Luckily, it was an A123, and the smoke was just coming from the melting wire insulation... if I had LiPo on there, I'd be in deep weeds!