When I first went to university I joined the Scuba Diving club partly I think because I had watched a lot of Jacques Cousteau programs over that summer. After learning the basics in a pool I, and all the other newbies, had to go for a medical to satisfy the insurance before I could go outside. I was given an appointment with a doctor at the local hospital who was also a member of the club. Part of the medical was a chest x-ray. This is actually a bit excessive but that is what the insurance people wanted. It was probably how the costs were kept down. We didn't have to pay very much about the same as a pint of beer.
I arrive at the hospital and am directed to the right waiting room. I think because the doctor was doing me as a favor I was the last to be seen. I went in the room and the doctor was sitting at her desk. She was a very attractive woman in her late 20's or early 30's. She was wearing a tight pencil skirt, black tights and a crisp white blouse under her white lab coat. She had her stethoscope around her neck but my eyes were drawn to the hint of cleavage I could see. I sat down and she ran over the basic health questions and then I was told to go behind a screen and remove all my clothes and put a gown on. I found undressing behind a screen a bit of a turn on, I was a horny 18 year old after all but I managed to keep myself in check (I think I could have kept my boxers on but I didn't) The gown was one of the old fashioned type that did up the back. I came out behind the screen and sat on the bed. The doctor told me to slip my arms out of the gown so that I was bare chested. She then checked my breathing with the stethoscope having her that close to me and laying her hands on me I got an erection. I probably went a bit red as well. I was worried that when I lay down it would show through the thin material of the gown and I was right. Now this is the point where if this were a fantasy the doctor would have helped me get rid of the erection by stroking me. She didn't. Instead she took the little hammer she used to check reflexes and gave my erection a sharp tap. This got rid of the erection. (I've since learned this is the standard NHS way to deal with an erection) I had the x-ray got dressed and went home.
Once home I got another erection and stroked myself thinking of the doctor in her crisp white shirt. Now when I see a beautiful woman in a smart white shirt I always think of the doctor.