This is a situation I'd heard about and always hoped would happen to me, well this was my day!
I was out grocery shopping one day and when I got back to my car, I noticed a man sitting in the car next to mine. Something didn't look right. I didn't want to stare but I was horrified and extremely turned on to see that he was masturbating! He saw me and didn't make any attempt to cover up. Since I am just about always horny (I am hornier, I think, than most women) I thought, here's a free show. I looked around the parking lot and was relieved to see that there was no one nearby. The man in the car gave his average-sized penis long, slow strokes, pulling on the foreskin, and would squeeze the head while he stared at me. He closed his eyes a couple times and started to jerk faster. I couldn't believe what I was seeing. My pussy was burning and I could feel my clit swelling. I think I stopped breathing.
Suddenly his body tensed and he shuddered, ejaculating all over his steering wheel. I heard a muffled moan coming from inside his car (all the windows were up since it was about 40 degrees out). As soon as he was done I got in my car and hightailed it out of there. I had a hard time driving home because of the pictures in my head and my clit was throbbing. I squeezed my legs together in frustration. As soon as I got home I masturbated lustily. I think about it every time I masturbate. I'd like to thank that man, whoever you are. You are so hot.