One word of caution here, although I am certain I am preaching to choir here, but still....
If you do bring snacks in, at least try to be discreet about it. Two or three protein cereal bars should be enough to hold you over for the evening (and should easily fit in your pocket, especially if you are wearing cargo shorts). Especially if you are able to ditch out and grab a piece of pizza or sandwich as well.
I just don't want people to start thinking they could bring in grocery bags full of food and/or coolers full of drinks. The last thing we need is the staff to really start cracking down on this and then not be allowed to bring ANY snacks in.
Again, just a word of caution.