Technically, AMC discourages bringing your own snacks to the cinema to encourage purchases from their own concession stands. That's why they offer concession discounts like the $5 small combo on Tuesdays and free refills for members. But legally, cinema employees can't arrest you for sneaking food in.  You don't even have to hide them since you're allowed to bring your own snacks. Just be mindful of cinema etiquette by not bringing hot food or any food that smells or crunches loudly. This can offend the rest of the audience.