The first time I remember having a climax was when I was nine, although I'm pretty sure I had them before that. My parents were leaving me at home alone for the first time while they went to a neighbor's to play cards. After my parents said goodbye and to make sure I was in bed by 10:00, I got into my summer sleep clothes (boxers and a T-shirt) and headed downstairs to the basement for an evening of playing with my huge collection of toys. I also made sure to bring my wristwatch, which I almost never wore, so I would make sure to be in bed before they got home. There was always something about having something on my wrist, whether a watch, bracelet or whatever, that gave me a tingling feeling in my crotch. Once when I was playing with a friend and he used some toy handcuffs on me, I got a little hardon, which he teased me about after grabbing it a couple of times.
So after going into the basement and playing for a while, I dumped out some action figures onto the floor and lay down to start playing. A quick check of my watch showed I had lots of time. For some reason I decided to put the watch on. I had a skinny wrist, and even at its tightest the leather band was a little loose. As I lay on the floor playing idly, I started getting fixated on the watch which moved around when I moved. Before long, I realized I was getting that tingly feeling and started moving my hips back and forth. After a minute or two of that, I started feeling as if I were going to pass out, but couldn't stop my motions. All of a sudden I had the most amazing sensation. I felt like I was exploding! As I started to calm down and my motions got slower, I realized how intensely enjoyable it was.
For a year or so after, I would try and recreate this feeling by rubbing on something a couple of times a week, but I always associated it with wearing that watch! It got to the point where I couldn't even put it on without having an instant erection, although that was the point sometimes. Fortunately, I got over it after realizing that it wasn't the cause, but I still have it in a drawer someplace!