Jon suddenly remembered how the stone worked. If you wished something, only you and the people who hear you know that you made a wish. Everyone else thinks that it's always the way the wish made it
Which means that the only thing she'd be in trouble for if his mom came in was the masturbation. Otherwise it'd be as if she was always a girl in a hot leather dress. There wasn't the mess that she could have made as a guy, so she quickly pulled the thong back and hoped her mom didn't notice.
"Come in, Mom!" she said.
Her mother opened the door, took one look at him, and was livid. "What kind of clothes are you wearing, young lady? I know we don't have anything like that around here...."
Oh, no. After the wish, Jon's mother thought there was a perfectly normal reason for Jon to be wearing leather. Normal in the sense that it has an explanation and nobody thinks it magically appeared. But that doesn't make it normal meaning that her mom was happy with it. Maybe the explanation was that he had a leather dress but was hiding it from her mother.
Still, that was easy to fix with a wish. As soon as her mother walked away, she said "I wish that my wish to wear sexier clothes just meant sexier than the boy's clothes I was having on, but something I could walk around at school with." Instantly it was done. She had on a pink blouse, skirt, and heels higher than she was used to, but nothing really outrageous.
She walked out of her room, right past her mother. Like everyone else, her mother still thought it was natural for her to be a girl and hardly even gave her a glance.
Since Jon hadn't tried to change back yet, she didn't realize that his original wish was still flawed. "Cheese" would only change his clothes back, not make her male again. So she left the house, preparing to see how it would be to be a girl, without realizing that she was in fact stuck....
