I had a group of players attempt to institute "the five word rule" in one of my games. The house rule goes something along the lines of: ANY npc that speaks directly to the party gets 5 words, not one more, to prove that they should not be killed immediately (if the NPC initiated a conversation by saying "hello, my name is blahblah, I will give you 10000 gold to tie my shoes", the npc dies as 'hello, my name is blahblah' doesn't convince the characters he should remain alive)
This got old. Fast.
I instituted stupid points.
The house rule goes something like this: When players do something that makes the DM entertain the thought of killing their character for sport, he instead allows the game to progress normally, but assigns the player a stupid point (the player rolls 1d8 and loses a 1: point of str, 2: point of dex, 3: point of con, 4: int, 5: wis, 6: cha, 7: 3 hp, 8: character misplaces an item of DM's choice (usually either the offending item or unclaimed loot the character happened to be holding if possible)
As far as stories, I've got one of PvP good players vs. stoopid player.
I had a nightmare player in one group who shall go by the name of Hopelessnoob (HN for short).
HN often played the stoopidist race/class combinations he could come up with, but after a year or two of going through characters at a pace unmatched by any other player I've had the pleasure of meeting, his reserve had run dry and he could only come up with 3-5 stoopid characters per weekly session.
HN was on his 4th character that night, for once a 'normalish' elven ranger who had a thing for his horse. The party came across a wooden door that was locked. Our mage/rogue couldn't open it after taking 20, and we needed to get in to find our objective (some module, they're all the same). In I (dwarven cleric of tempus) and the party's half-orc tempus-worshipping paladin were all too happy to appease HN when he jokingly said "use me as a battering ram!"
The DM said "are you saying that in character?"
HN: "No. Ah, why not, yeah, I say it in character."
Immediately the dwarf and half orc jumped the elf, tackled him to the ground, each took a pair of limbs, and proceeded to break the door down with the elf's face.
It took 40 minutes in game and nearly exhausted all of my character's spells, but we opened that door.
The DM never questioned the LG paladin or CG cleric's class abilities/faith/whatnot; we all knew it needed to be done.
note: no elves were harme...killed in the making of this story.