Adderral. If it can make a half-brained alcoholic srat girl interested in spending 9 hours studying freshman chemistry then it can sure as hell keep you up for a marathon video game session. And you'll get so into it that you won't feel any need to get up to eat, drink, or even use the bathroom. Remember: effectiveness scales linearly with dose, and the heart palpitations are the sign that it's working!
(Note: this is a joke. Do not actually do this to yourself, dextroamphetamine has a known neurotoxic effect in non-ADHD users even at therapeutic doses).
Serious answer: I don't eat at my keyboard ever as a rule. I hate when my fingers get dirty or greasy from food, and then it grimes up the keyboard and never comes off.