Hermione sat down in her seat to watch the Muggle movie, but something didn't feel right. There was an annoying itch on her bum. Were this her house, or even her hotel room, she would have flipped up her skirt and plunged her hand down into her panties, but this was an airplane, and there was someone sitting next to her. It would perhaps be...disconcerting, not only for the person next to her, but also for her parents. So Hermione placated the itch by reaching down to her skirt and raking the fabric with her fingers. She attempted to eliminate it, but it just seemed to move with her fingers. Just as she thought she had it pinned and sent down her scything fingers, it shifted again.
Then Hermione had a wicked thought; she began to herd the "itch" towards her crack, and when it was sufficiently close, she threw herself back in the chair. Now the irritating itch was stuck in her buttcrack, where it stopped bothering her, and she could focus on the movie. Vaguely, she wondered whatever had become of the tiny American she had shrunken. Odds were the Magical Congress of the United States of America would have gotten involved almost immediately. The jerk would have had a Memory Curse put on him, he would be regrown and then he would continue his life as usual. MACUSA wouldn't be able to punish her; not only was she not a citizen, but she was underage, and with no formal magical training whatsoever. The worst that could happen would be a stern warning from her own Ministry. The only possible problem would be if he were somehow transported across the ocean with her, at which point she could be arrested. But it was probably nothing to worry about...
Unbeknownst to her, she was right. She wouldn't be arrested, and indeed couldn't, because the Magical Congress was entirely unaware that such an event had taken place. Nobody would watch the security footage, and there were no public records indicating Miss Hermione Jean Granger was a witch. And while the disappearance of a Muggle (or, in American terminology, no-maj) might be the subject of a minor police investigation, there would be no one to suspect sorcery. For all intents and purposes, the tiny human now stuck between the mountainous buns of Hermione Granger was a legal non-entity. Speaking of which...
Hermione began to wonder as to the nature of the "itch" she had felt earlier. Since the plane had long since taken off, she unbuckled her seat belt and stood up, so she could go to the bathroom to check on it...
Choice One: You fall out of her panties and into her shoe. Hermione remains unaware, but now you must deal with her sweaty, confined, dirty-sock-clad feet
Choice Two: Hermione goes to the bathroom and finds you. However, she may think you're a pervert, and subject you to cruel and unusual punishment...