Jon pushed his D-cup breasts into Karyn's as he kissed her over and over, trying to maneuver on top of her. Just touching his skin was sending him over the edge.
"Jon, stop. We've got to get ready for school. We don't have time for this," Karyn said.
"I can't, Karyn. I'm just so horny right now. Come on, let's do it, please?" (Didn't say "pretty please".)
"We just did it last night. Believe me, I loved it," she said, with a smile, fondly remembering having sex with Jon the previous night, which didn't actually happen until the stone changed reality to make it so that it did happen. It was the explanation for why Karyn was waking up naked in Jon's bed. "But I don't think your bed will be able to take it. One more bounce and it might collapse."
Suddenly, Jon's breasts grew, becoming E-cups.
"Karyn, don't say that!" Jon yelled, realizing that his breast-growing wish that was only supposed to be affecting Karyn was still affecting him instead.
"Say what?" she asked.
"Bounce!" Suddenly, his breasts got even bigger, becoming F-cups! Now they were noticeably bigger than Karyn's.