Lipo Safe/Bag

[MapMaker53]

Good thing it wasn't in a public restroom. Was it your keys or coins in your pocket that shorted it out somehow?

 

[No Sheep Designs]

It was the kind without connectors (see attached photo). Apparently, the negative terminal on these types of batteries is the ENTIRE outside of the battery, only shielded by the plastic coating and sometimes a small rubber washer near the top. If the plastic and/or rubber near the positive terminal becomes torn or damaged, it's very easy to bridge the small gap between them. I'm guess that's what happened to me.