"Orange, Longbottom," said Snape, ladling some up and allowing it to splash back into the cauldron, so that everyone could see. "Orange. Tell me, boy, does anything penetrate that thick skull of yours? Didn't you hear me say, quite clearly, that only one rat spleen was needed? Didn't I state plainly that a dash of leech juice would suffice? What do I have to do to make you understand, Longbottom?"
Neville was pink and trembling. He looked as though he was on the verge of tears.
"Please, sir," said Hermione, "please, I could help Neville put it right--"
"I don't remember asking you to show off, Miss Granger," said Snape coldly, and Hermione went as pink as Neville. "Longbottom, at the end of this lesson we will feed a few drops of this potion to your toad and see what happens. Perhaps that encourage you to do it properly."
Snape moved away, leaving Neville breathless with fear.
-Prisoner of Azkaban, Ch. 7 "The Boggart in the Wardrobe"
Snape is such a nice teacher, isn't he? Even before I loved Snape(as much as I do now), I always thought these scenes were freaking hilarious. I love how he's so scary and bullies Neville mercilessly. You know, I think the reason J.K. Rowling has Snape be so mean to Neville is to make us doubt that he's purposely singling Harry out. See, he treats Neville just as bad as Harry, if not worse... so we know he just hates all Gryffindors. Well, except for one...
And back to scariness... he's so sexy when he scary. I'd make him mad on purpose just so he would get all up in my face and talk in his dangerous voice... And then when he wasn't expecting it, I'd lunge my head forward. ;D
