I walked into the women's dressing room at the Tae Kwon Do studio, even though I have never been in there before. When I opened the door, there was a guy from my psychology class(who I don't know) inside changing. He apologized for being in the women's dressing room. I told him it wasn't a big deal and that I accidentally was in there too. We looked outside the door, on the base of the wall. There was one of those shoe store mirrors that are at angles. It was set up so you could see under the door from outside the changing room. The guy told me to pull down my pants and put my butt against the door, which was the kind of store changing rooms with the panels that allow you to partially see through. I stuck my butt against the door and looked between my legs and under the door, at the mirror. I could see the impression of my bare ass through the door. I pulled up my pants and the guy and I were amused, but concerned that people could spy on us.