This happened when I was in high school. I didn't have my license yet, so I'd have to walk home if I felt like going home while in school. Since it's not a very long walk, I didn't mind. One afternoon I was angry for whatever reason and decided to skip last period and go home. As I walked along the road, I felt a car slow down behind me. It came to a stop right next to me and the driver rolled the window down. She had shoulder-length brown hair with blonde highlights. She took her sunglasses off and asked me if I wanted a ride. I recognized her as a girl I'd had several classes with. In fact, I had a couple with her at the time. I found it a little odd that a girl who had a boyfriend would offer a mere acquaintance a ride (especially a male one), but I thanked her and slid into the backseat. I didn't want to make her uncomfortable or anything by sitting in the passenger's seat (she probably wouldn't have been, but still). And I didn't know if she was planning to pick up a friend or something along the way. I would've felt weird sitting in the front with a friend of hers in the back.
Anyway, for the first minute or so, I just stared out the window not saying a word. She rolled her window up and turned the air conditioner on. She asked where I lived, and I told her. I looked at her and for the first time realized how hot she was. I didn't know why I hadn't realized sooner, but I was taken aback by her looks. I leaned forward a bit and caught a glimpse of her tanned, glistening legs. She had on a denim skirt and a top that, while nice, made it difficult to tell the size of her breasts. That didn't matter, though. She was beautiful.
I felt my penis stiffen. I had my jacket on my lap because it had become too warm to wear it. I positioned it so she couldn't see me rubbing my cock through my jeans with my other hand. The head got through the hole of my underwear and was rubbing against the zipper, which was a bit painful, so I undid my fly and took my throbbing hard-on out. The air conditioner was pretty loud, so I don't think she heard. I rubbed the head with my thumb for a minute before switching to my palm. I looked at her long fingers wrapped around the steering wheel and wondered what it would be like to have them wrapped around my cock. My eyes started to water and I looked down to see that the head had swelled to about twice its normal size and was almost purple. I felt my balls tighten and proceeded to have one of the most intense orgasms of my life, spraying a jet of cum into my jacket. She pulled into my driveway a minute later and took out her cell phone. She held it to her ear and turned around, pursing her lips. I leaned forward and received a kiss on my cheek before again thanking her for the ride.