I can't believe I didn't post this one already:
http://www.fmstories.com/stories/magic/GreenBook.txt (BE, IB, TG, MC, Body swap)
Reading from a magic book, two boys unlock spells to make a girl's breasts bigger, her complexion prettier, and her body sexier.
I especially like the part where the first girl to get this treatment reaches for her razor to shave her legs and armpits as usual, only to realize her body doesn't need shaving anymore. I think I like it because of the way the woman - whose beauty is usually the product of great effort like hair, make-up, grooming, dieting, exercise and generally trying to stay young - instead becomes beautiful
as the natural state, and gets a lot of levereage against "normal" women in the competition for men.
It's a bit like
this story (which I may or may not have posted before), where the protagonist's enhancements become irreversable after a while - for instance if you'd cut her hair, it would just grow back to it's original enhanced length. If you'd force-feed her 100 hamburgers, her waist would just shrink back to its thin state. (Those particular things don't actually happen in the story, but I wanna explain my point without spoiling too much.)