Hmm.. When I was 14-15, I was gaming with a group of close friends. All of the same age. Our DM, I'm not sure how (this was before the internet, and I know it wasn't through posting in FLGS, kept bringing "new" players to the game. In most cases, it was fine. There's two occasions, however...
-The old Porn Dude. That guy was in his late twenties. And he revealed very quickly that he made his living dubbing porno flicks. He had 50-60 VCRS hooked up together, and he dubbed porno films, selling the copies of movies he rented. And, well, his characters were weird as well. He lasted two sessions, probably because we expected him to bring some tapes the second session and he didn't. Hey, we were young.
-The other was the "weird couple". It was a couple years later, so we were 16-17. That was before White Wolf, which is probably why they were playing D&D and not V:TM. Their characters were elves, brother and sister. We were in FR. At some point, for some reason, our Mage cast an area Dispel Magic. They.. Became drow. We had just finished a rather extensive and deadly incursion in the Underdark. We slaughtered them No quarters, no questions. They called us immature and left. The DM, who I think taught the chick was hot, was mad at -us-. Weird.
And while I never had a problem with drunks or otherwise as players, I had a DM who was.. Under the influence of something. White powder. In the middle of a description, he stopped, and started counting initiative (that was in 2nd edition, when you counted 1, 2, 3 and people who had that initiative acted on their numbers). Now, nobody had -rolled- init, and we all looked at each other weirdly. He smiled embarrassingly, and called the session off and went to bed.