You don't think it can happen, but it can happen.

I was a senior in high school overseas and a new student teacher came into our English class. She was one of those vibrant persons, too much energy. As she got comfortable with the class, she spoke about herself a lot. She was overseas for a semester before returning to finish her teaching degree.

This one day, she had on a dress and during the class she leaned against the teacher's desk, and then to all of our surprise, she lifted herself up to sit on the desk. She was totally commando, not a stitch on under her dress, as she wiggled herself into position she flashed the room.

I know that she didn't do it on purpose, she was just into her class and didn't think about what she was doing. But for those of us where 17 at the time, it was our first full view of girl crotch and you can't forget it.