With my sisters and cousin
Our house was a split level with my bedroom downstairs along with a 3/4 bath, and the family room. The rest of the bedrooms and the other bath were upstairs. I liked having the downstairs because it was much cooler in the summer and it was kind of "my" area of the house. One day near Christmas, as 17 year old boys without girlfriends often do, I went into the bathroom to jack off. Nobody else was home at the time, but I thought I had locked the door anyway. I removed my jeans and underwear...