They see it as both their right and their duty to be unruly. They wear silly clothes, do silly things, make silly noises, and permit themselves the silliest descent into an uncharacteristic excess of shameless jingoism. And then they wake up the next morning feeling even more ashamed than they do most mornings when they wake up and remember the night before. I suppose it’s fun in a mildly sadomasochistic sort of way. It also makes very popular TV viewing, especially among those to whom shameless jingoism is routine.
This is one of the medleys around which the second half of the concert is built every year. The tone is about a hundred years out of date, but even students like to pretend now and then.