Ahahaha... a prom is a social event held at, er, human schools, I guess. Its where all the teenagers get to funny business while the teachers just stand there to watch it with perverted smiles. And a date is well... someone who you take to a prom, usually one of the other gender. There are exceptions of course.

And yeah, you wear those sort of clothes to prom. Formal looking ones. Its annoying, really.