Rachel called her best friend, Mark, who luckily lived right next door. "Hey Mark, wanna come over? My aunt just sent me a box of chocolates from Abu Dhabi."
Mark was over in just a minute. He was a year older than her, and going to the local junior college. "So Rache, what sort of chocs do they have in Abu Dhabi?"
Rachel showed him the box, but not the key. He looked at all the chocolates and chuckles. "Naughty chocolates from the Arab world? Why am I not surprised?"
Rachel was more surprised that he hadn't noticed her new breasts, so gestured to them. "What do you think of this?"
Mark blinked. "She sent you an Arabic push-up bra too? You've got a cool aunt."
Rachel shrugged. "Have some chocolate."
Mark smiled and picked out a white chocolate pair of buns. "Ooh, white chocolate ass." He popped it in his mouth and chewed, and Rachel watched as his ass started to shrink just a tiny bit, his waist narrowing along with it.
Mark paused. "That's weird." He blinked at the box. "I thought I just took that chocolate." He selected another white chocolate ass and popped it in his mouth, then watched as a new chocolate appeared in the box as his ass continued to shrink. He took the new chocolate and popped it too, then the one after, and the one after that.
Then his pants fell down around his ankles and his boxers as well, exposing his incredibly tiny, skinny narrow ass.
"What happened?" Mark gasped, then clutched his almost nonexistent butt with both hands. "My ass!"
"White is shrink," Rachel explained. "Dark chocolate is grow." She showed him the lid of the box.