Dance
"I can teach you how to dance, you know."
"How the hell did you get in here, Loony?"
"Well, the door wasn't locked, and that seemingly used to mean that no one occupied the room."
"..."
"You were doing fine, until you fumbled with that one step. It's supposed to be---"
"I know how it's supposed to be! Slytherins may seem uninterested with everything around them, but they're not brain dead, if that's what you think!" With every word, his voice reached a higher octave than before, sounding more paranoid and irrational rather than intimidating.
"Seeing as you're trying to learn dancing from a book, I'd think otherwise."
An astonished pause, blinking and then a frustrated sigh ensue.
"Who made you the expert on dancing?"
"No one. I appointed myself."