"I wish that I had a device which could change a woman's breast size to anything I wanted." The stone flashed, and a 1950's style ray gun appeared on the ground. It had Cleavage Ray printed on the side, with "For All Your Cleavage Related Needs" printed in smaller letters. There were various dials for setting cup size and other factors.
"A Cleavage Ray?" said Karyn. "You are such a boy. You can wish up any device you want, and you make something that makes a girl's boobs bigger?"
"Not just making them bigger," said Jon. "I can make them any size that I want. I figured that, if the stone couldn't reverse the wish you made, maybe the Cleavage Ray could."
"I didn't think of that," said Karyn. "Lets try it out. These boobs are killing me."
Jon pointed the ray at Karyn, set the gun at her original size and fired.