In the mid-2000s there was a really great full service provider in DC, who was also an amazing yoga teacher.
He had an amazing ability to make you so flexible and relaxed that you could engage in something he called "shurging." He would start out topping you and then slowly, but surely insert his balls one at a time. I had my doubts when he proposed it to me, but it turned out to be a really amazing feeling, particularly as his balls went in and out. His dick was better than average-sized and his balls were relatively small.
He never proposed anything that he wasn't willing to do with you himself. He was a great top and bottom, so I decided to try it, but it was too painful for me when I tried to push my balls in.
It's been years since I tried this and only with him. Anyone else tried this? Know any providers who can do it well?