I am not sure this is to naughty but I have never told anyone that both of our children were conceived in the back of our minivan in the parking lot at my husbands workplace.
He is a very successful business man, time is one thing he never has and when we wanted to conceive we were told that saturation during ovulation is the key so I told him that I could be on his schedule and come to him. He was a little worried about it but enthusiastic about my ideas and probably turned on quite a bit by my willingness to do it in the back seat. We have one of those models where the rear seats fold flat and the last row can just be removed. One additional feature is a full size mattress fits right in there with a little bit of the sides rolling up but does the trick nicely. I would pick him up from work for lunch and we would go somewhere and park then jump into the back area and make love like two teenagers on a date. There is a Walmart not far from his work with a huge parking lot and we would just pull into a spot near the back and get naked. I could tell he was completely into it by the way he was doing it, he loved the fact that someone might see us because he always wanted me to be totally naked and sometimes he would mount be from behind while I held on to the front seats.
It was quite a great time but I do not think anyone ever saw us, maybe noticed the van moving around some but that is about it. I even still do it now and then for him by dropping the kids off with my mom telling her I need a mom day to go run errands, unfortunately the mattress does not fit with the seats in there so we have to do it on the floor with just a blanket down. I do miss the morning, noon and night sex to make it happen, we sometimes did it four times a day and I would even roll over in the middle of the night and climb on top of him.