my first masturbate SeXStoRY

I was a young boy barely twelve years old. My neighbor who was a year older than me had been teaching me about sex but I still wasn't too sure about it. I was starting to grow hair and I noticed that my dick would get big quite often. I really didn't know what caused it to get big and hard but I knew that I liked how it felt and I wanted others to see what I could do. My older s****r would regularly have friends over and I wanted them to see this big dick that I had. I would put on really tight shorts, get hard, and then walk infront of them for them to see it. I didn't really know what I was doing but I knew that when I did it my dick would get even harder and start tingling. My bedroom was right next to the bathroom and anyone walking by could see me in my bed. One night when my s****r's friend was there I was in bed and was hard as a rock. I wanted her to see my dick so I got on top of the covers in my underwear and tried my best to get her to look. I realized that just laying there she would never stop to see it so I put my hand on it. My fingers were wrapped around my balls and the palm of my hand was on my dick. I started jerking it all around. I had never masturbated before and I didn't even know what that was, I was just trying to make alot of motion and noise so that she would stop and see my hard dick. After a few minutes I started thinking that it felt really good with me jerking on it so I kept going. She would occasionally walk by but she never noticed. I kept jerking it though because it felt so good and I had never felt that before. Finally she walked by and noticed me jerking my big dick through my underwear. She stopped and looked with really big eyes. She said, "Oh my god" and then walked off giggling like most girls would do. Once I realized that she had seen me, my dick suddenly started getting really tight. My body starting fealing weird and I didn't know what was happening. I was scared but I liked the feeling so I kept jerking it. Suddenly it felt like my dick exploded and my body started shaking. I was shocked but I loved the feeling. All my nerves in my back and legs were jolting like I was getting shocked and then suddenly my body just fell into a peaceful state. I felt something wet in my underwear so I put my hand under there and felt this nasty, sticky stuff on my hand. I was scared to death. I didn't know what happened and I didn't want anyone to know what I just did in my underwear. I just laid there with my hand on my cock wondering what that could've been. So that was my first masturbate experience, the first of many to come.