Back in the day, my brother and I used to buy Mt. Dew slushies from Sheetz and see who'd get a brain freeze first. Though it was only slightly competitive in nature, it wasn't a full-on 'brain freeze" contest. This contest, presumably at resort or waterpark of some kind (the bathsuits are the giveaway), involves rapidly slurping some sort of possibly alcoholic frozen beverage as fast as possible. Chug, chug, chug, except through a straw.
I'm not going to ruin what happens at the end, but let's just say "brain freeze" contests probably aren't the best idea. "Pete and Pete" in real-life, on YouTube. Hope everyone is OK: