"Do you remember me telling you we are practicing nonverbal spells, Potter?"
"Yes," said Harry stiffly.
"Yes, sir."
"There's no need to call me 'sir,' Professor."
This is another one from The Half-Blood Prince, during their first DADA class with Snape.
When I first read this, I just wanted to go "OOOOHHHHH". It's such a pwnage moment. I love Severus to death, but Harry was being such a smart-ass there. Although, I did get really mad at Harry for disrespecting Snape like that. Plus, Snape must have felt really humiliated. Regardless, it's a hilarious scene, and it sucks they didn't include it in the movie.
