The guy who was my very first DM (and whom I still play with a fair amount, though I'm usually the DM now) would typically polish off a six-pack of beer (back then, usually Old Style or Guinness; Elephant malt liquor is now his poison of choice) during a game session. He used to get to be a pretty irrational DM after a few beers; fortunately, he's cut back some.
This past Saturday, I was playing D&D, and the host (who was also the DM, different guy from above) had more empty beer cases in his apartment than you'd see behind a college bar on Sunday morning.