A formal dance held on Christmas night when a Triwizard Tournament is occurring. This is basically Christmas prom where the same usual goes for four hours straight.
Ranka: Hey Susumu, will you take me to the Yule Ball?
Susumu: Sorry Ranka, I can't. Konata in the grade above me asked me.
Susumu: Sorry Ranka, I can't. Konata in the grade above me asked me.
by The Real Driller June 25, 2017