Ooo, I've got some good ones:
1st edition D&D:
1st level Ranger, name unknown. DM starts with us chasing a thief - I use my crossbow to bring him down. I get arrested and hung without trial by the city guard for an assassination that happened the previous week by crossbow.
This kind of thing happened a lot when that DM was running things. I didn't play with him too much...
1st level Monk, name unknown. Joined a gaming group of VERY mixed levels - this was 1st edition, with Unearthed Arcana, and I remember some of the players tossing off chain lightning spells into each other's amassed armies.
Myself and one other player are walking along a road. The DM tells us to "save versus paralyzation." My friend gets turned to stone, I save. I go running for a ditch - anything that can turn a player to stone is WAY out of line for a L1 character. DM tells me to save again, I fail.
We spent the next 5 hours bored out of our minds listening to the epic battles of the other players, then let the DM know we were NOT happy with his style, and that he could stick his DMG, well, eric's grandma wouldn't approve of what we told him.
MERP:
Spent two hours making characters. Came across a path in the woods. Got eaten by a worg within 2 rounds of combat, in which neither of us could even touch him.
Never played MERP again.