LostSoul said:
So let's make one:
Any time you do something in-game, the player to your right can demand you roll a d6. If you roll 1-3, you fail/can't narrate; if you roll 4-6, you succeed/can narrate.
There. That rule covers everything.
How about a real rule? The only thing this rule really does is give the potential to make any game completely silly:
Player 1: I'm going to leap off the balcony, grab the curtains, swing over the head of the minotaur, then strike the floor with my hammer so hard it cracks open causing the minotaur to fall through into the room below so I can just grab the gemstone from the pedestal.
Player 2: That sounds cool. You succeed.
Dungeon Master: Huh? You can't do that!
Player 2: Well, I like his idea, and since there are no rules to cover this and I sit to his right, I get to make the call as to whether he can do it. I say he can.
Player 1: Awesome!
DM: But...
Player 2: All right, my turn. I'm going to run up the wall, hang upside-down from the ceiling and shoot arrows at the minotaur through the crack in the floor.
DM: You can't!
Player 2: Well no rules cover that, so you can make me roll for it, or just let me do it.
DM: Roll
Player 2: A five, I succeed.
DM: I'm leaving to go play WoW.