Do I Smell Smoke?

Back in my line mechanic days, I was working on an old air cooled VW bus. I was charging the battery, which was located in the RR of the engine compartment. It had been charging for quite a while with me working on something else at the time. I was talking with one of my fellow mechanics when I decided to disconnect the battery charger. He was standing right next to the charger, so, I asked him to turn it off. He flipped the switch and said OK. Well, instead of turning it off, he had turned the charger to the "Start" position. When I reached inside and grabbed the negative cable, we had a nice hydrogen explosion which blew the sleeve off my work jacket and sprayed battery parts and acid everywhere. Good thing I didn't have my head in there! My ears were ringing for a while after that stunt, and we had to give the bus owner a new battery.