I read this as students who are under should be mindful around tailgate areas, and those of us who aren't under 21 should just be sure to use common sense and use cups. And maybe we shouldn't walk nearly to the gate with a half full Dixie cup this week.
This aside, this is a topic/subject that has rapidly changed in the last few seasons. Tailgating has become so huge that it's occurring in parking areas that it never did before until the last two years. It's a "price" of football success, and a good one in my opinion that we have a real gameday atmosphere around campus that didn't exist 5, 10 or more years ago.