"Oh, hush Jon. I wish you wouldn't be a crossdresser."
Jon felt a strange sensation come over him. After the stone's glow dissipated, he looked down to get the shock of his life. He had breasts!
He (or rather she) turned to look at the hallway mirror and saw a girl that looked a lot like the woman in the magazine that he accidentally swapped clothes with, except that Jon had brown hair instead of blond.
"Well, isn't that an interesting way of granting my wish," Zoe said. "I've always wanted a sister." She paused for a moment. "But, we can't be calling you Jon. That's not a very good name for a girl. Is it?"
"Zoe, please ..." Was that Jon's voice? It sounded so much more ... girly.
"How about something close, but different? That way it'll be easier to remember." She paused again. "Okay, I've got it. I wish that your full name is Jennifer Michelle Smith, but you'd prefer to be called Jenna." (His full name was Jon Michael Smith.)
Jenna knew that something was wrong. Her name was Jenna. But she knew that her name used to be Jon, and that she used to be a guy, as weird as that sounded. She still remembered all of this, because she heard Zoe's wishes. She also remembered that she still had the swapping ability. And that was good, because she had to stop Zoe from making any more wishes.