The sudden appearance of mud on Jon's clothes revealed what was really going on. Karyn had wished that he'd look like Shannon.
Having mud on him must mean that that's what Shannon looks like. In other words, somewhere off in the city Shannon got splashed with mud--and therefore, Jon, who magically looks like Shannon, would get splashes on himself without having to encounter a mud puddle first. They were connected.
How far would that go? What if Shannon changed her clothes, or put on makeup? If Shannon took off her clothes and took a shower, would Jon also suddenly find himself naked and soaking wet? Being covered by mud is a lot like being covered by water, after all. Clearly he wasn't exactly the same. His body didn't start walking by itself because Shannon was walking and people could see that, so there had to be some limit.
And there was another question. Jon had explained the stone. The stone changes reality. Jon's memories weren't changed by the wish, and only changed when she made another wish asking for just that, so Karyn had no clue whether Jon remembered his new status being real. But everyone else did. Jon was now a 15 year old who was magically connected to Shannon and everyone else thought he was supposed to be like that. That was even stranger than just the connection itself.
On the other hand, Jon's mother still remembered Jon. And she obviously didn't think that the Shannon lookalike was supposed to be Jon. So in the new reality Jon couldn't just have been magically connected to Shannon since the day they were born. Maybe Jon got connected to her yesterday, or this morning. Naybe if you just use the stone for a spell, something that works like a spell works, it doesn't change reality after all.
"Jon?" said Karyn.
"Yes?"
"You've been answering to 'Jon' all along. So that's your name, right?"
"Of course it is," she replied.
"Do you remember what happened?"
"With the stone? Sure, you turned me into a girl who looks like Shannon."
"But you agreed to go on a date with Ralph."
"Of course," said Jon. "I'm a girl now, and he's a guy. This is what people do."
"But you're not a girl," said Karyn.
"I wasn't a girl a half hour ago. I am now!"
"I get it," said Karyn. "I made you think like a girl but I never wiped your memory. I honestly don't know what other people think happened to you. Your mom knows who Jon is and didn't recognize you, so I can't have created a world where you've been Shannon's lookalike all along. We've got to find out until I can reverse this. Come along." Jon was still doing as she said, so that should work.
"Where are we going?" asked Jon.
"We're going to find out why you're changing to look like Shannon." Then she gaped. "Jon, your clothes!" Jon's sundress was loose and Jon's panties had fallen down her legs. "Shannon must be going to the bathroom. I hope this only goes this far. Can you pull those up?"
Jon seemed to be able to get dressed again, which made Karyn a little relieved. Jon would be changed to look like Shannon but he could still wear clothes and change his appearance himself. And it didn't seem that Jon actually had to go to the bathroom in the middle of the street--the magic only extended to appearance, after all. Clothes were appearance, but going to the bathroom isn't, except when it involves removing clothes.
"Where do we go?" asked Jon.
"I'm not sure," said Karyn. "No, wait, I can ask the stone for the answer. But whatever it is, it looks like you're stuck thinking like a girl until I figure things out. And I don't know about looking like Shannon--I forgot to set an end condition for that wish...."
