Probably the worst experience I had in gaming involved alchohol (although that wasn't the root of all evil). It happenned when I was about 14, but I was stone sober, so that's no big.
One of my friends decided to run the original Temple of Elemental Evil. Somehow, pretty much everyone in the HS who'd ever played D&D found out about it and this guy couldn't say "no". We ended up with (IIRC) twenty-four (24) players.
Fully _half_ of these showed up mainly to get blitzed, chat, and kill some orcs. Anyone even passingly familiar with ToEE knows that's not a good mindset.
Didn't really matter, though. To the [dis?]credit of my friend, he actually hosted a five hour session. We made it as far as the entrance to the Moathouse. Green slime dropped on one of the drunks and dissolved him.
Apparently, he was the leader because they decided to move the party elsewhere. By this time, the DM needed a few beers, too. Game over.
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Our gaming climate is such that a couple of beers/glasses of wine/coolers is no big deal for the players. I don't drink while I DM and the other DM doesn't drink at all. I'm about the only one who _might_ be able to scare up some rare herbs but I never cared for 'em.
About the only DM aid I use is a 52 oz. cup of Chai laced with copious amounts of ginko, ginseng, and echinacia (energy, clarity, and throat aid, respectively).