It never happened, I am a girl, it's less frequent and easier to hide lol. However I did walk in on my brother, he was 14 I was 12. I was so freaked out I couldn't hide it so when my parents asked I couldn't come up with a good lie and just blurted it out. He got in trouble and he hit me in the stomach the next day in revenge. I didn't tell on him for that because I shouldn't have said anything to begin with. It was super disgusting by the way!! Guys at least lock your doors! To clarify I am talking about doing something by yourself not doing something with a boyfriend or girlfriend :)