lol, depends on your age. I would bring my own cooler with some food and things of that nature. A Hibachi grill would make a hell of a difference too if you have one. If you're of age, I'd say bring some beers or liquor, cuz it's like $7 per beer at 6 Flags (In Buffalo anyways) a bunch of money, a camera to take some pics of the good times, and if you're part of the Organic Institution like myself, a little green bag. It's also wise to bring a sweater, a change of clothes, Don't forget to bring a towel

a hair comb, and a sweater just in case it get's cold. Umbrellas also help even when it's not raining, because 9 out of 10 times, the lines for the ride have no shade from the sun, so it gets hot waiting in line.
Have fun!