A few summers ago I participated in a short-lived Palladium Robotech RPG at the local hobby store. The gamemaster was a friend of mine. Our party also included the owner of the store, one of her employees, and a young man I would later learn had a habit for playing particularly psychotic characters. We were playing a new squad of the Earth defense forces, using Veritech fighters (jets that could transform into robots). The entire party were humans except my character, a Zentraedi alien born on Earth (Britain, specifically) named Zaderac. The lieutenant in command of our squad was the hobby store owner's employee; the rest of us were all privates.
On our first mission, we were sent to defeat a rogue general who had taken over an old Robotech factory underneath a mountain. Remember that, as it becomes important later. We encountered a few older model Destroyers (non-transformable robots) along the way that we easily annihilated with our shiny state-of-the-art Veritechs. Zaderac was, in fact, the one responsible for taking out most of the enemies through careful use of his Veritech's missiles. The Veritechs we were using had an armament of 60 missiles. That also becomes important later. Zaderac quickly reached "ace" status.
We infiltrated the mountain base, and discovered a missile depot we used to re-stock our Veritechs with missiles. (We also discovered a young girl with strange psychic abilities.) We then travelled to the bottom of the base, where the general and two bodyguards were waiting. They were using slightly more advanced (but still out of date) Destroyers, and we easily took out the two bodyguards, leaving just the general. This...is where everything went to hell.
Our fourth player, Mr. Psycho Character (who hadn't done much RPing anyway) decided to quickly take out the enemy general by firing all sixty of his Veritech's missiles. Bear in mind that he was firing sixty missiles beneath a mountain. He announced to this action to the gamemaster, rolled to hit... and rolled a natural one, which in Palladium terms is a critical miss. Every single missile went wild, missing the general. Our lieutenant moved next and decided the best way to minimize damage was to fire all sixty of his missiles at the missiles our psychotic friend had fired. He rolled to hit and rolled a natural twenty. The missiles not only found their targets but exploded spectacularly. The end result was the entire mountain came down and buried our Veritechs under tons of rubble. We were trapped in our robots for about three days, and we all developed claustrophobia (in addition to one or two other psychoses), and then the psycho player quit the game, and the campaign ended not long after that. And to date, that's the only time I've ever had a mountain dropped on me.