I was at a con a few years ago, along with my gaming group (we lived near a reasonably large con). Three of my groupmembers and I all joined the same game, a low/mid-level D&D dungeon crawl (this was before 3e). There were two or three other PCs who we didn't know in the game as well.
Anyway, we start going through the dungeon, being very cautios, having the thief check for traps etc. After a few fights we get to a fork in the tunnel, and there is a demon statue at the point of the fork. Our thief checks for traps . . . nada. Our fighters start to move down one path of the fork, but I stop them (I'm playing a Wizard, I think I was level 7 at the time - the highest in the party) and say something along the lines of:
"Wait, we should make sure that this thing won't animate behind us. It would really suck to be caught between an animate statue and whatever we have to fight down that tunnel. If it can animate, we should attack it now, so we can deal with itself. And if it is just a statue, then nothing happens, and we can just keep going, right?"
After a bit of debate, everyone agrees with me, everyone gets set, and our fighter throws an axe at it.
Now, what we didn't know was, the DM that we were playing with at the con normally ran a very high level campaign set in hell, and she had just taken her favorite personally created demons and added them to the dungeon we were in as statues on a whim. We were never meant to fight them.
So, when we attack the demon, our DM just bursts out laughing (it was made for fighting parties of approximately 16-18th level). The demon animates, and proceeds to tear through the party. Its killing more than one PC per round, and everyone is running around wildly like headless chickens trying to get away (and all of my friends are yelling at me for being an idiot). For some reason (I think my DM was a bit generous) I had a book of infinite spells on me, and used one of them to teleport away with whatever was left of the party. Of course, I was using a spell that was much higher level than I was normally allowed to, and so I took a lot of damage, and I believe I went permanantly insane.
