We're not sure, but we're almost certain college football is an excuse for Americans to congregate in large numbers and get really drunk in bars during the day. In other words, it's what St. Patrick's Day is to us.
So, sure enough, Katy Perry turned up in Oxford, Mississippi where she backed the local team - Ole Miss - to beat Alabama. As it happens, her team lost but she decided to console herself by... well, check out the Vine.
In fairness, she knocked that thing back like a pro and some young fellows were good enough to catch her when she dived into the crowd.