First Time Fully Naked in a Public Place Nude and Stroking

I was out with a few of my friends one sunny summer day at the local elementary school playing some 6 person baseball. After a few hours everyone had to head on home for dinner. My family was out of town that weeks visiting family and since I was 17 I stayed home. I had been horny all day and had gotten off several times before I even joined my buddies at the ball field. I told then that I was going to stay and hit some balls against the backstop for a while since I had no reason to head home. They said fine and rode off on their bikes. I had no plans on hitting the baseballs when I said it. However I didn't lie since I hit my own balls a little later. After they left I walked around the school buildings to see if I could find a place to have some fun with myself. I finally located a spot between two of the buildings where I could stand and no one could see me unless they walked up on me. I had jacked off in a lot of places but usually I just pulled my cock out of the zipper and went to town, or I would drop them down to my knees and do it. This particular day I was especially horny. 17 year old's are always that way. I slid my pants to my knees and started to have some fun stroking and seeing my reflection in the windows of the classroom across from me. I decided to pull my shirt off and continue watching myself stroking. It looked like I was completely nude in the reflection. It was then that I decided to just take it all off, socks, shoes, and pants and underwear. Since then it has become a lifelong obsession when I jack off. I took everything off and continued to stroke away. Then I went a step further and walked away from my clothes. Now I was 10 feet away from anything that would hide my nakedness. The thrill was intoxicating and I was hooked. Finally as I was getting close I walked back to the place by my clothes. Back in those days I liked to cum by humping and not stroking. I usually humped my mattress or a table top or floor but none of those were available. I got down on my knees and laid on the warm, smooth cement and started humping the cement. It felt great too. Warm and smooth and my balls were loose so they were rubbing on it too. About 10 slow strokes is all that it took and I had an amazing explosion of cum that went up against my stomach and smeared on the cement while I continued until I was hump away. Finally satisfied with myself I sat up and used one of my socks to clean myself up. Got dressed and started to head home. As I got on my bike I saw a new set of guys heading to ball field to play. I had cut that one close. Since that time I have done it nude outside in at least 50 other places.