When I was in my early twenties, I took a job modeling for a sculpture class. It lasted for over a dozen sessions. I was in great shape and I imagined that I would enjoy showing off my body to a class full of aspiring artists. I had taken a life drawing class in college, so I sort of knew what to expect. When I was hired, I was told to wear a jock strap. My first evening, I was pleased to see that the majority of the class were women in a range of ages from my age to middle age. I changed into the jock and wore a robe which I took off when I started to pose, at the direction of the teacher, in a series of positions for the class to do quick sketches.
At the first break, one woman spoke up and asked if we could do away with the jock strap covering; we were all adults and she would like to have a nude model to work with. A quick vote showed that everyone agreed, and I said that it was ok with me (actually I was totally excited by the idea -- I liked showing off my uncut cock at that point in my life, and I thought it would match the classical sculpture that they had seen). During the ten minute break, I ran off to the men's room and quickly masturbated and came, to make it easier to stay flaccid. I went back into the classroom, took my position on the platform in the middle of the students, took off my robe and stood naked in front of a group of people staring intently at my body. It was a very strange experience.
Since it was a sculpture class, the teacher finally set up a pose that I would hold through the entire semester. Though holding the pose was hard and tiring, it was harder to keep from getting an erection. I would have to jerk off on some breaks, and things would get hot when people would come up to get a closer look at various parts of me, or a woman would chat with me while I was nude. I'm afraid I was a bit removed socially because I was so concerned about not letting my cock get hard. I succeeded in never getting more than a semi (that happened fairly regularly) but it took a lot of discipline.
The sculptures began to take shape as the classes went on. And it was great to walk around on a break and see everyone's work develop. One amazing moment was when the teacher was a bit critical of the sculpture of an attractive mature woman student. He said that she had made my genitals too large. It was physically accurate to my body he said, but in classical sculpture the "pudendum" was quite reduced in size because they thought it looked more harmonious that way. She said she understood but liked it the way she had made it. I fought to keep my breathing under control.
They took a bunch of polaroids of me (this was quite a while ago) so that they could work between classes. I asked that they be returned to me at the end of the class and I wrote down my address. One day in the hot summer, after the class was over, there was a knock on my door. It was the woman who was faithful to my anatomy returning the photos. I invited her in for a cold drink. We had a beer. She asked to see my body one more time. I was happy to oblige... and to have great sex with her the rest of the afternoon. She came back to see me, when she could get away from her husband, over the next 6 months.