I still love to masturbate
When I was 13, my two sisters were 15 & 17. We lived in an old house that had an unusual set up. I would exit my bedroom into my parents bedroom and go down the hall to the bathroom. My sisters shared a bedroom, and it had two doors, one that entered into my parents bedroom and one that came in off of the dining room. If I kept walking down the hall to the kitchen and dining room, I would go into the dining room in the dark and would watch my sisters changing in their rooms through a keyhole. I would make the nightly trek down the hall whenever I heard either or both of my sisters going into their rooms at night. The dining room was on the opposite end of the house from the living room, so if my parents were to come down the hall I would hear them and could go into the kitchen like I was getting a drink. I would go to the dining room every night and watch my sisters take their clothes off. They would strip naked and get into their night clothes. As I watched them I would masturbate, sometimes coming on the floor and sometimes I'd dash down the hall to masturbate in my room where I could do a better job of it. I did this for a couple of years without them ever knowing it. I can still remember it very vividly and when I do I still get hard and sometimes will masturbate thinking about it.