Also, be forgiivng of GM errors. If they make a call in the middle of combat that you know doesn't gibe with the rules, but it isn't a big deal, son't bother with it. You've got a limited amount of time to play the scenario, and spending 20 minutes of that debating over an obscure rule that would only have changed a couple boxes of damage on an NPC isn't worth it. Around the house that sort of rules lawyering may be expected, but at conventions it just bogs things down.

I've seen what's available at tourneys. The one at ICON had a variety of ready-access food (a commissary at the Student Activities Building & Student Union; an outdoor burger & hot dog grill on the lawn outside the gym building, which also had a snack bar; several well-placed snack & soda machines; and just ont eh other side of the local LIRR tracks, a bar & grill that made deliveries, a take-out pizza place, a Baskin Robbins & a 7-11), but I'm talking about the rudeness of talking with a mouth full of whatever, or just being plain careless. Books, dice, character sheets & the like have all been irretrievably damaged because of one smart-@ss who forgot to eat lunch before the game.

Also, don't forget the Alka-Seltzer & Pepto.

And YES, I fully agree with just being able to roll with things. But there's a limit to everything.