I, too, dig the student-teacher concept. For some strange reason, I fantasized about the drama/stagecraft teacher at my high school even though I didn't find him attractive. I think he was fully aware of this fact, too, because sometimes he was at *ahem* half-mast. I also got slightly different special treatment when I finally took one of his classes (stagecraft, drama is ick). He was a really fun and awesome teacher, but unless you count sitting on laps, neither of us crossed the line.
Yeah, anyways, I've always wanted to do it during a lunch break in a classroom with the door locked and windows blinded on the teacher's table, rowr. With a guy not unlike my young math teacher who "accidentally" slipped in a picture of a sex shop when he showed us his trip to singapore as a slideshow.