If your school was sitting on top of a Hellmouth, would you be sticking around for math class? The Scoobies did. Despite knowing a demon could kill them at any minute, they stayed in school. All of this goes to show that a diploma from Sunnydale High really means something.
Cordelia: You'll be okay here. If you hang with me and mine, you'll be accepted in no time. Of course, we do have to test your coolness factor. You're from L.A., so you can skip the written. So let's see...vamp nail polish? Buffy: Over? Cordelia: So over. James Spader? Buffy: He needs to call me! Cordelia: Frappachinos? Buffy: Trendy but tasty. Cordelia: Josh Tesh. Buffy: The devil. Cordelia: That was pretty much a gimme, but you passed!
Joyce: Okay, have a good time! I know you're going to make friends right away, just think positive. [Buffy leaves the car] Joyce: And honey... [Buffy turns around] Joyce: Try not to get kicked out. Buffy: I promise.