Stupidest thing I've done so far was to buy a mechanical mod and not asked the clerk in the store what the difference was between the hybrid adapter and the 510 adapter. He put my RSST on the hybrid adapter and handed me back the mod and off I went. On the way home I unscrewed the RSST from the hybrid adapter and screwed in my AeroTank mega to the hybrid adapter.
I took about 2 or 3 vapes on it and noticed that the mod was a bit warm. The first thing that came to my mind was that it was going to explode and take my nose or a couple fingers with it, so I quickly unscrewed the aerotank and dumped the blazing hot battery into my hand and melted a tiny bit of skin, then I tossed it into the back seat of my truck so as to get it as far away from me as possible in case it exploded or vented on me. I then pulled over and tossed it into the bed of the truck. Just noticed this last weekend that it did something funky to the rear seat fabric too even though it didn't vent.
Anyway, not asking the clerk for the information that I should have asked about is probably the stupidest thing with regards to vaping that I've done so far. What's really really stupid about it is that normally I'm the person that will bore the clerk to almost tears with all my questions but that day I just didn't ask like I should have.