My wife and I were getting massages about once a month through a friend of hers we'll call Bridget. Neither of us ever got naked, but this one moment did happen to me.
I had some loose-fitting shorts on. Since I have sinus trouble, she was massaging my forehead area. Man, did it feel good. I also found it's an erotic area. I knew what was happening, and I wasn't covered by the sheet. I looked up and said, 'Sorry about that.' She said 'That's ok, it's normal.' Suddenly, I went from embarrassment to extra excitement. I felt like 8 feet tall down there. I did cover up with the sheet, but that didn't conceal anything.
When the massage was over, I apologized again, but told her she got me ready for my wife later. She smiled.
This happened for 2 more months. At the end, I said I needed to use the bathroom. She seemed to understand. I went in and exploded all over the place. She probably knew what I was doing.
On another occasion, I was laying on my stomach and was afraid I was going to cum all over the sheet! Fortunately I didn't.
I wonder if anyone has by accident?