I was 18 and very much a virgin when my brother lost his driver's license. Terry was 5 years older than me and since I didn't have a job, I became his chauffeur. I would take him and his girl friend out and they would drink and dance while I drank soft drinks or coffee and watched. At the end of the evening Terry would tell me to find a dark alley or someplace to park so he and his girl Jenny could make out. They didn't make me leave, so I would watch in the mirror and end up with a raging hard-on by the time they were done. The up side was that I learned a lot and got free shows. This probably started my liking for voyeurism that continues to this day.
Then one night my brother passed out before we could find a place to stop. I didn't realize this until I had pulled down an access road along a set of railroad tracks. When I stopped Jenny said, "This is a nice private place, but he is out."
Before I could say anything she got out and hopped into the front seat alongside me. Jenny looked across the bench seat at me and said, "What do you think when we get, ahhh, busy back there?" nodding at the back seat.
Looking her in the eye I figured the hell with it, I would tell her the truth and said, "Honestly, Jenny, it makes me horny as hell. I always go home with a hard-on after watching you two have sex."
Jenny leaned over and put the palm of her hand on my cheek, "that has to be rough to deal with every time we go out." Her hand felt like flame on my cheek, I nuzzled into it, enjoying her touch. "What do you do about that?"
I smiled at her and said, "I jack-off of course."
Jenny laughed and said, "Of course you do. What else would you do?" Then she gave me a knowing smile and asked, "If I gave you something to look at can I watch you jack-off? I have never seen that."
I was dumbfounded to say the least, but answered, "Take your blouse off, play with your pussy, and ok, it's a deal."
Jenny didn't say anything but started undressing. Jenny was 22 at the time and very trim. Later, I found her measurements were 32-22-36 and she was a C cup. Jenny had a flat belly and her titties stood out, passing the pencil test easily. As she undressed I reached over and flipped her long brunette hair back over her shoulder, telling her, "I don't want to hide this view." She laughed.
Jenny leaned back against her door and crooked one knee up onto the seat. She took one nipple in between her finger and thumb and started rolling it and tugging on it. I didn't realize a nipple could stretch that far before watching her. She reached between her thighs with the other hand and sloooowwwllly drew her middle finger up the edges of her outer lips, barely splitting them. She had her hair trimmed very short, almost gone short, which was unusual in those days.