When I was in my early thirties I would sit in parking lots outside shopping areas and masturbate while watching the women in their shorts going in and out of the stores. I would always cover up if someone came near my car.
One day while I was enjoying myself I noticed some guy approaching from behind me so I put my coat across my lap. The window on the passenger side was down and he stopped to talk. He told me not to stop on his account and I played like I didn't know what he was talking about. We chit-chatted a little more and he told me to go ahead and do what I was doing. Again I played like I didn't know what he was talking about.
Finally he asked me what size my cock was. I figured what the heck and told him. He wanted to see it because he claimed he never saw one that big. I had never showed my cock to another man but decided why not. I moved my coat out of the way and showed him my cock. Within seconds I was so turned on and showing a full erection. For the first time I sat there and masturbated for another man and it was great. He stood there and watched me intently waiting for me to shoot my load, which I did.