You buy it at the counter anytime before or during the scheduled showtimes
You have to buy the largest one or be a Stubs member.
You can just leave the movie, go out to the concession stand, wait in line if there is one, when its your turn give them your used container and they will refill it. Refills are free.
You bring along a friend who doesn't want to watch the movie or watching so he doesn't care about leaving the film you also want to make sure that dude's polite so they actually give you a refill because I'm not sure you can get refills.
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