"Minerva McGonagall: The Yule Ball has been a tradition of the Triwizard Tournament since its inception. On Christmas Eve night, we and our guests gather in the Great Hall for well-mannered frivolity. As representatives of the host school, I expect each and every one of you to put your best foot forward. And I mean this literally, because the Yule Ball is, first and foremost… a dance."
January 1, 1970
https://en.wikiquote.org/wiki/Harry_Potter_and_the_Goblet_of_Fire_(film)