I am a male in my 40s, a bit of an exhibitionist and I love to wank. This afternoon I went into town with my wife to do a bit of food shopping. I work in an office in the city centre and one of the perks is that my staff-pass opens the barrier to the car park - so we can use it at weekends when parking would otherwise be very difficult in town. Not that I usually use the car to shop, I usually cycle, but today we needed a sack of potatoes from the market and that is a bit difficult to carry on the bike. Unfortunately, I had forgotten that the car park was in the process of being resurfaced. We had an email round on Friday warning us of this, but it had slipped my memory. So we got in to town and found the car park full of machinery. The office is right in the centre of town and off a road which is pedestrianised except for buses and access. The entrance to the car park runs between our office and a neighbouring one - so I decided to stop there in the car park entrance - since nobody was going to be coming in or out. We turned the car round so it was facing back towards the street and I stayed there, in case it had to be moved, whilst my wife went and did the necessary shopping. She would then come back and wait whilst I went for the potatoes. So I was left sitting in the car for some time watching all the shoppers trooping past just a few yards away. The weather today was, although with some heavy rain showers about, and it was quickly obvious that the nipple count was quite high! Plenty of young females about who were not wearing a bra - always a pleasant sight at this time of year. The view was enhanced by a sudden, heavy, burst of rain which added some wet tee-shirts to the fun. After watching a few passers by bouncing pleasently with clinging, damp tee-shirts I was getting quite turned on and my cock was stiffening nicely. I was just wearing a pair of shorts and a tee-shirt myself and soon started to squeeze my erection through my shorts. I pulled up the left leg of the shorts so I could slip it out and started to rub more vigorously. I was finding this quite a turn on, wanking away with crowds of people passing only yards away, but not very comfortable with my erection forced over sideways. So, as I got more aroused and consequently felt more daring, I undid the buttons and zip of my shorts and got it out properly, pushing my pants down below my balls. Now I could masturbate properly, although I was in a pretty vulnerable position if anyone should walk into the car park entrance, or even worse, come out of the car park behind me. They would be on top of me before I could do much to cover up. The risk of being caught, of course, added to the excitement. I was nearing the point of no return when I saw my wife across the street, returning with cluster of carrier bags. She is not into this sort of thing. She finds the idea of being watched in any sort of sexual activity a complete turn-off. But she is well aware of my proclivities and quite use to catching me masturbating. So I slowed down a bit in order to hang on until she arrived. I timed it to perfection and shot my load just as she opened the car door. She gave me a long-suffering look and commented "extraordinary!". I cleaned up a bit on some tissues and adjusted my clothing and went to help her get the bags stowed away in the boot and then went and did my duties with the potatoes.