Harrier Dude
Living the dream
Good try - it's the scene in the gym on the first day of school, where Brad and his friends are standing around and Jennifer Jason Leigh swings by. When she leaves, Rich (Nicholas Cage, credited in the movie as Nicholas Coppola - and yes, he's the nephew of Francis Ford...) says "Brad, your sister is really turning into a fox.."
When bored, you can study the entire script here: http://www.dailyscript.com/scripts/fast_times_at_ridgemont_high.html
There is also a scene that isn't shown in many versions of the film where they are at All American Burger discussing Mick Jaggers guitar pick. It's right after/before "No shirt, no shoes, no dice".
I think he had a line there, too.