Take advantage of the privacy

You have a seat on Rebecca's bed and take in the scene.

There you are, naked but for a small towel, sitting in Rebecca's bedroom. There's a small desk with schoolwork on it, a couple dressers, and a nightstand. It's pretty neat; laundry's in the hamper, trash in the trashcan, blanket tucked into well-made bed. One wall is filled with neatly-arranged photographs of Rebecca's friends, and there are other pictures of her scattered about, especially photos of her traveling around the world with her (very attractive) family. The room smells fresh and clean, and even though the AC is on, an open window lets in fresh air.

You notice a door connecting to a bathroom, and you can see from your vantage point on the bed that there's another door on the opposite side of the bedroom. You remember from walking down the hall that the bathroom is between two bedrooms. She must share a bathroom with one of her sisters, you conclude.

As you look around the room, your thin towel loosens, and you're struck by a taboo thought. You allow the towel to come untucked, falling away from your lap on the bed, leaving you completely naked. The thought of being nude in this space starts to make you hard but also frightened and embarrassed.

Suddenly, you hear the sound of a closing door. You're still alone in Rebecca's room, and you realize right away that the sister on the other side of the bathroom must have just gone into her room.