A few days ago I noticed a new co-worker of mine was a vaper. He had some kind of old, ratty looking mech with some kind of tank I'm unfamiliar with on top. This guy doesn't strike me as the type of person who would be responsible with a mechanical, but trying not to be judgmental, I kept quiet. So yesterday a friend of mine says "look at that guy, what's he doing?" I look over and see this guy dancing around, frantically pulling everything out of his pocket. Out comes an 18650 battery, with a key WELDED to the end of it, still throwing arcs! By this time, his pants were actually SMOKING!!! We go over there to investigate, and he had put a fully charged battery without any kind of case or covering in his pocket with a bunch of change and his keys. The old ratty battery no longer even had the plastic shrink wrap sleeve on it, just a silver cylinder. When it was cool enough to touch, we examined it, and the positive terminal had completely burned away, and it had burned a hole in his pocket about the size of a half-dollar. After lecturing him about using a battery case, we asked to see the battery in his mod. He pulled it out and it was in worse shape than the one that shorted out in his pocked. No insulated wrap, big gouges in the side, burnt spots on the positive end. All we could do was warn him to get new batteries and go about our business. I have a feeling our warnings fell on deaf ears. I even showed him my little $0.99 battery case. I can understand someone not being completely knowledgeable about all the technical stuff, but isn't this just common sense? Sigh.