I have a hobby room upstairs. In it, I have a small charging table for all my random little fucking batteries and their attendant plugs and adapters. I plugged in a little 750 mah battery into its charger and set about fiddling around. This was not a 3rd party battery.
I never leave this shit unattended. I was working on something at the other table and looked over at the battery I was charging. It was swole and getting swoleier. It wasn't swole when I plugged it in!
I thumbed the main power switch off to the power bank it was plugged into, then unplugged it from its own adapter.
Off to the races! It popped and went off like a big flash bulb from 1950. It filled the room with dense white smoke in an instant. I was holding it via its wire leads and glanced around the room for something to dump it into, and tossed it into the middle of my leather chair. One of them cheapo $100 units from Sam's or whatever. This decision phase was just a few seconds. I ran the chair and the REALLY pissed off battery outside. I packed the chair with snow and threw the battery into a snowbank.
This all happened very, very quickly...seconds, really. If I had fucked up and grabbed the battery with my hand, it would have burned a giant hole in the flesh, and I likely would have tossed the battery or dropped it and caught the room on fire.
It was a small battery, too. About half again larger than this one and twice as thick.
What was amazing is how fast it happened, and how much smoke it produced almost instantly.
CHECK YOUR SMOKE DETECTORS and replace them! They have a service life of what, 3 years? This shit could have gotten way out of hand very quickly if I didn't have my wits about me.