Stands for "pretty, popular and proud."
Most often used to describe a girl who recently realizes she's hot/sexy and abruptly becomes friends with all the populars. After this miraculous event a PP&P usually puts tons of new photos of themselves on MySpace, Facebook etc. They're usually in innocent poses, but sometimes they feel daring and show a little cleavage.
Brianna: Since when did Chloe and Ashley start hanging out?
Taylor: I don't know, but Chloe's been updating her pics on MySpace. Did you see that one of her in that really tight tank top?
Brianna: Oh jeez, we've got a PP&P on our hands.