Yeah guy. Right on the money with this one. If I have a beer or two handy, I find they make me better at skill-based games (online Gears 2, mostly). I think it's the same thing as above: you don't overthink and in my case I tend to attack more aggressively while still staying halfway competently. Get the drop on way more folks.
Rock Band, obviously, is tailor made for alcohol abusers. I'm sure everybody's seen the 2 am failboat that roars to life when everyone gets back from a bar, hammered, and tries to play Expert in a burst of overconfidence.
Stoned is poorboots for video games, I find. Sure, they're more FUN... but I'm not nearly as skilled, that's for sure. I suppose RPGs would be tailor made for marijuana, except the new ones all have horrendous anime-face voice acting that psychs me out; I would enjoy the inventory management and collection aspects of the game, but I can't endure the horror of Japanese children screeching about valour and whatnot.