Plot:
Harry gets a mouthful of himself during sex.
Snape doesn’t slow down.
Debate follows.
"How's it?"
"Hot, and tasty?"
"I meant my COCK, Potter. Not your culinary review."
"Hot, then." Harry flushed and hesitated for a while, searching for the right word to say, "And, uh, really amazing. Your cock, I mean, it's in my... ass."
"ARSE," Snape corrected, deadpan, "Or anus, if you’re trying to sound smart. But clearly, using the right words isn’t your thing."
"I’d rather stick with ASS, thanks."