"I wish," said Chad, "that the past was changed--not a change in what people remember, but a real change to the past--so that instead of this happening to me, it happened to Jon instead."
Given Chad's lack of wish experience, it wasn't surprising that he'd screw up--he hadn't figured out that he'd probably hate the new result as much as the old. The magic of the wish went back in time and slightly tweaked things....
"Come on, Chad!" said Jennifer. "I came here so you could help me make a wish. Here, try something." She handed the stone to him.
"Dude, I don't want that to happen to me" said Chad.
"You don't want what to happen, Chadie?"
"I don't want what you did to happen to me! You said 'I wish, that until I say the word Periwinkle, that I would be an incredibly sexy 16 year old girl wearing a tiny string bikini.'" And Chad had the rock in his hand at the time, so he transformed.
"I did not say anything about periwinkle like that!" replied Jennifer.
Upon saying the word, Jennifer immediately transformed back to Jon. And now he was looking at an incredibly sexy 16 year old girl, who was approaching him and from the way she walked and stared at Jon, was obviously attracted. And she was holding the stone.
"W-- wait!" said Jon. The girl was hot, but she was really a guy! It was really Chad. "Chad, snap out of it... you're just influenced by the stone! Sigh... that's probably useless. You don't remember being Chad, I can tell."
"Chad?" replied the girl. "My name is Charlene!"
"Just give me the stone back so I can fix this!" said Jon.
"I wish you'd pay attention to me instead of thinking about that stone..." said Charlene.
And Jon did forget. Chad's wish had come true, wiping out and replacing his own timeline. Now Jon was male, but Chad/Charlene was the one transformed. The only person who knew about the stone was Karyn, who had no way to know it was lost in Chad's home.
Then ten months later, Charlene picked up a broken crayon in Jon's room and accidentally said the word "periwinkle". Suddenly she was Chad again and remembered, and Jon could no longer pay attention to Charlene, so he remembered too. It wasn't exactly the previous timeline with the people reversed--for one thing, the stone wasn't in Jon's room this time. But some things were similar.
Jon, who was making out with Charlene, suddenly found himself with Chad and let him go in horror. Chad shook his head, trying to clear it, as Jon backed away. What had Jon done? Chad had been a girl for the past ten months and in that time Jon and Charlene had....
