I'll go first!
I've been playing a spooky co-op game called Pilgrim with friends lately. It's a dungeon crawler with monsters that all respond to different items, you go into dungeons and light your way with wall torches, collect treasure, buy items at the shop, and continue on. So we've been playing for a while and for the first time we have a lot of money, so we decide to buy an item we've been curious about for a while: The Mystery Box. No description, no idea what it does, just a $200 price tag.
So we buy it and we gather around excitedly, thinking surely when we open this there will be some kind of special item or buff, like maybe we get to fly, or it'll give us all extra health, or a magic sword or something, right? It's so expensive it's gotta be good. So the person who bought it activates it and BAM my whole screen goes bright purple-white. My view shifts to third person (this happens when you die) and I'm observing a scene of pure carnage. I'm dead, two other friends are dead, and the person holding the box is flailing around madly while it emits bright purple laser beams in all directions that slice through any living thing with a single touch.
Sufficed to say, the one person who kept their distance was probably on to something.