Back when I was 14 years old, I lived in a small house in New Jersey. I lived with my parents, and my sister. My sister, who was 15 at the time, was a fine looking girl to be her age. Ever since I started puberty I was fascinated about watching her and sometimes I would masturbate to the thought of her. I learned to masturbate when I was about 13 years old and have loved it since. One day, my parents were home and we were home from school. I think it was Martin Luther King Day or something. I woke up, excited about not going to school, and went downstairs to get some breakfast. I was eating breakfast while watching t.v., and then I finished and went up to my room. I was playing the Nintendo 64, because in 1997 that was all we had. That was before everyone had cell phones and their own computers, so when I was home from school, the thing I would do was masturbate. Since I had only been masturbating for about six months, it was still a new and fun thing I loved to do.
Being fascinated with my sister, I would sometimes like to spy on her. When I usually did this, I never expected to see her changing or anything else, I would just watch her read or something. She had a high door, about three finger widths, so you could see under for the most part. But this one time I walked to her door, she was sitting on the floor, leaning against the bed, and sticking her fingers inside her pussy. I immediately became very excited and rock hard in a instant. She had a beautiful body with nice boobs and a perfect pussy. I lay on the floor peeping under her door for a while as she slowly masturbated, and gradually speeded up as the time went by. I was sitting there for about 10 good minutes before I noticed her start to squirm around and I could see that she was having a noticeable orgasm.
I was so excited but I noticed that she was getting up so I quickly got up and went to my room.
When I got into my room, I got naked fast, laid on my bed, and started jerking as hard and fast as I could. I came in about a minute and a half. I quickly cleaned up and went back to her room. She had gone downstairs, so I snuck in there and saw a little wet spot on the floor.
I had never been caught by her until I was 15 and she was 16, and she really did not care, and sometimes we would 'get caught' on purpose by each other. It was fun, but now we are both married and live in different countries so obviously it won't happen again.