Depends on the type of game. Fast, furious and aggressive(i.e FPS, fighting, racing) means Rockstar, Relentless, Coffee, inVigorate, Pizza and all other manner of junk and caffeine-laden beverages along with a few friends to taunt/punch in the face (get a little twitchy after a while).
However, for more laid back experiences (RPG, RTS, turn based and... other) beer, weed, more Rockstar, Pizza and the knowledge that I don't have to work or even speak to anyone for the next 48 hours. Sometimes it's good to be antisocial, no amount of beer or pot can withold me from killing someones face if they interrupt me during epic-game-marathon-time.