My mother would take every opportunity to knock on the bathroom door and say, "What are you doing in there?" it became a problem as she would do it whenever I went into the bathroom. I ended it in one day. I waited for her to get on the toilet, and then I would bang on the door and shout hey what are you doing in there?" I did this a couple of times, and my mom told me how disrespectful that was, and she was realizing the whole situation as she was scolding me. She never did it again.