Oh my god, I think I remember this movie from USA Up All Night.
At the end, does the nerdy hero get shrunk down and somehow get into the hot girl's panties? Then the climax (ehem) is him literally slipping in and out of her, bringing her to an orgasm in the middle of class?
EDIT- okay, yeah, I should really watch all the clips first. This is obviously that movie. The director seems to have quite a pantie fetish!
