We were staying with relatives for a few days and exactly 2 weeks ago today, we went out for a meal. My girlfriend had let me choose her outfit of denim skirt with beige top and underneath a black bra, black pvc suspender belt, black satin panties, black seamed stocking and a full length pink nylon slip. The outfit was completed with black stilletto heels. It looked sexy without being tarty. When we got to the restaurant, I was fingering her in the car park and told her I'd arranged for someone to fuck her in the adjoining hotel afterwards. I said that he would be in the restaurant but although I would know who it was, she wouldn't. All evening we were talking about it and on a couple of occasions she said she hoped it would be certain guys in there (especially the young black barman). When we left I pretended to take a call and that the hired stud had to cancel. It was a role-play but she didn't actually know if I was serious. She certainly seemed to be up for it. We then drove along the motorway with her skirt around her waist for all the lorry drivers to have a look as I slowly passsed them. At one point when we were going to turn round, I drove into a service area and accidentally drove through the lorry park. Lots of the drivers parked up had a good view of her suspenders and panties. We rather stood out as a car driving through the lorry section. It was more exciting as it was genuinely by accident. When we left the motorway, she wasn't comfortable going back to the relatives to fuck, so we went to a car park within a park. It was now semi-light and we lowered the seats where she got on my lap and pulled her panties to one side. As I entered her someone from the other car there walked by and looked in the window. I expected her in all honesty to panic and demand I drove off. Instead she started to really fuck me rather than the other way round, looking directly at this guy wanking his cock while she bounced up and down. She came all over my cock, so much it was runnig down my leg. Her panties were absolutely soaking. As she got off me, I pulled her panties off her, wound down the window a little and handed them to the guy. He then wrapped them round his cock and came in them. We drove off leaving them wth him as a souvenir.