Year ago I lived in an apartment where by bedroom window overlooked the bedroom window of the neighbor. My floor was about a 1/2 floor higher than the building next door.
The girl that lived there was about 18 or 20 and would constantly masturbate on the bed. I had to adjust my venetian blinds and make sure that I had the lights dimmed in my room, but phew.... she used to do it at least once or twice a day! She was VERY small breasted and was always clean shaven. Personally, I rarely ever insert anything into myself but she had a huge fake penis she would regularly take. Once, she rolled up a sock, rolled a condom over it and shoved that inside!!