It all depends...I got a real clean life style, so it's never drink or smoke. It's usually music or the tv. I gotta have some kinda noise going on in the background or I can't concentrate. Most the time, I'm not even paying attention to what's playin', but I gotta have it there or I go crazy.
Occasionally, if I'm really just not feelin' it, I'll surf the web and find work other people have done and then I'll get into that "this dude sucks, I can do what he did 10x better and kill his shit" and then I'll just go after it. It all depends on the project and what time a day it is. I usually do my best work late at night under pressure.