Last summer, I was watching TV in the living room when I heard some splashing from the neighbor's yard. I glanced out the window and saw the neighbor's daughter in their pool with one of her friends. She was about 17 and her friend looked about the same. I stood there and watched them for a few minutes, getting a little horny thinking about them in their bikinis, but I didn't have a very good view so I went up to my room.
I opened up my blinds enough to see out, and from there I had a perfect view. Not only could I see their pool, but also their deck. My room was pretty dark so I knew no one would be able to see in, so I pulled my desk chair up to the window and watched them swim around for a while and eventually get out to lay in the sun. Seeing them laying there with their skin shining in the sun and wearing their tiny swimsuits, my penis grew to it's full length and was straining against my shorts. Since I was home alone I pulled off my shirt and kicked off my shorts, leaving me in my underwear that now had a big wet spot in the front. Sliding them down, my rock hard penis popped out, flinging a small drop of my precum in the air.
Completely bare, I sat back down and leaned back and started stroking myself while watching them. It felt good like it always does, but there was something extra knowing I was watching someone without them knowing it. I was probably doing this for 10 minutes before the friend rolled over, and I got a good look at her large boobs that were held tight by her top. Just thinking about that got me ready to cum, and I blew a huge load all over my chest. I cleaned myself up and got dressed and went back downstairs.
Every day after that, I would wear nothing but a pair of gym shorts, and would watch and wait for them to come outside. When they did I would go upstairs, get naked and masturbate over them. One day though, the neighbor was alone and when I went upstairs, I saw that she was tanning naked. This got me incredibly horny, so I rested my feet on the windowsill and stroked as fast as I could, cumming in about a minute. I wasn't nearly done, so I sat there and waited, and once I felt I could go again, I started playing with my penis to get it hard and masturbated to another orgasm. I thought I was done, but she rolled over and I was stiff again in seconds. Her boobs weren't as big as the other girl, but seeing her bare pussy made up for it. By the time she wrapped up in a towel and went inside, I had four loads worth of cold cum drying on my chest. I took a shower to wash all of it off, then went back downstairs and fell asleep thinking about her.
All of this went on at least 3 times a week for the rest of the summer, and I don't think I have ever cum as much as then. Hopefully, I will have another show to watch this summer and I can do it even more.