Many years ago, right after my wife and I were married, we were on a trip with another couple. We had gone to a business conference in another part of the state. The other couple, being more senior in the business, had offered to drive.
As we headed home from the conference, it was just after dinner and dark outside. My wife and I were sitting in the back seat of the car. The car was a small sedan, so we were sitting near each other. My wife and I had a blanket across us on the seat. As we all chatted about the conference and things to do in the coming week, I guided my wife's hand to my crotch. She caught on, quickly and quietly starting to rub me through my pants.
Having been at a business conference, I was wearing dress slacks that were quite thin, so she could readily feel my dick through them and grab it to rub it. Pretty soon, I knew I had to have more, so I pulled my zipper down. She looked at me with one of those 'you must be kidding' looks. I kept on talking with the couple in the front seat and guided her hand underneath my underwear.
Then she got a little smile on her face. I think she decided to see if we could do this without the other couple noticing. She began to slowly rub my dick up and down with the flat of her palm. It was getting a little harder for me to concentrate on the conversation, but I kept it up. Pretty soon my wife wrapped her hand around my dick and really started stroking it for me. We had rearranged the blanket some, so it wasn't obvious what was happening, plus there was lots of stuff in the seat with us, as we were coming back from a weekend away with coats, bags, etc.
Our friends just kept looking forward as we talked. My wife kept on stroking me. By this time I also had my hand on her crotch, but just rubbing her through her panties. I couldn't do her at the same time. That would become way too obvious! Pretty soon she really had me on the verge. I had grabbed some napkins from our fast food stop and stuffed them in my pants. She squeezed my dick really hard as she stroked me, knowing from my twitching that I was really close to cumming. I tensed up and shot my load into the napkins and onto her hand. It was tremendously exciting to do that right there in the car with other people who didn't even know what was going on two feet away from them.
That was an even better end to a good business trip!