This sort of event is a landmine. It needs to be policed. That's Nia's professed reason for showing up, at least. And, sure, she's keeping an eye out to make sure no one is made uncomfortable (hypocrite), but she also definitely participates - with the skill of someone who spends a lot of time dancing with herself in front of the mirror (sorry to her roommates). She's gotta perfect her form for prom.