and thats how he ruined the roleplaying game......

[CaptainBirdseye]

The worst wrecking of a campaign I ever DM'd was in a game of MERP, while waiting for their contact to turn up in a bar -

One player tried to mug a hooker upstairs and got KO'd with a candlestick
One guy tried to drink too much and ended up unconcious outside for the next bit where...
The remaining two guys got bored and started a fight, one of them tried to flying kick the bar man off of a table, rolled the worst fumble i have ever seen, tripped, and paralysed himself from the neck down.
And the last guy, forgetting the description of the party's contact, just heard the word "Sword" and shouted "Cheating bastard!" before setting him on fire.

Weeks of work completely wasted...

 

[Hieronymus]

I remember something from Castle Greyhawk. One of the levels is a giant bee hive. My thief, Otto, had a Smoking Bottle, a magic item that continuously spewed out smoke if the plug was removed. I said to the DM, "Beekeepers use smoke to subdue bees. I'm putting on a Necklace of Adaption (which would allow me to be able to breathe anything) and uncorking my smoke bottle." She ruled that all of the bee people would become catatonic. We held their Queen hostage until they gave us all of the treasure from that level. Since it was a module, I didn't really ruin any hard work on the DM's part, but I still felt weird, though.

In a Traveller game, we came across a hidden planet with technology that could grant anyone anything that they could think of. It was basically a mind controlled wish machine. My character wished for a ham sandwich and *poof* he had a ham sandwich, a really tasty one with Grey Poupon mustard. Using a ship that they gave us, we blew up their high tech level planet that the GM had worked on for weeks using their own Planet Busting ray, Death Star style. Then we directed the ship into a star and escaped in our own smaller ship. We rationalized it to the GM by saying that they would have brought a terrible imbalance to the Imperium and thrown the Spinward marches into chaos, but I think the real reason was that as players, we didn't want god-like powers in a science-fiction game. Oh, that and we were jerks.

 

[EvilEgg]

A kid we played Mazes &Monsters with started freaking out... things went really bad... Tom Hanks played him in a movie.