Very Unusual Ejaculation

He is around 38 years old, white, medium height, slightly thinner than average, keeps his hair short, shaves most of his light body hair including his genital area, and works in the high-tech industry. He has a girlfriend, and I am married. His girlfriend seldom 'puts out', and my wife says her hormones have shifted, so she's no longer interested in sexual activities. So, he and I, although we don't think of ourselves as gay, enjoy playing with each other very much. We don't kiss, do blowjobs or any of that. We just like our mutual masturbation. He likes it rough, and sometimes I do too. We generally edge each other for an hour or so, then one of us goes too far and cums. The other then receives some more attention until he comes also. I particularly like ball massage, and glans rubbing. That's when someone, male or female, rubs the palm of their hand over the tip of my dick. Oddly, the sensation is stronger with oil than dry. This glans rubbing business is hard to take. At first it makes one squirm and want to get away, but in a while, it transmutes into a combination of gonna cum or gotta pee feeling that is quite delicious and can keep one on the edge for quite a while. My friend likes to be fisted, and I'm happy to do that for him from time to time. We have also experimented with sounding. I once worked a length of sterilized aquarium tubing all the way into his bladder. He orgasmed with the tube all the way in, and nothing came out. The ejaculation was blocked by the tubing. The other night, as I was rubbing his rock-hard penis, and keeping him just below the threshold of cumming, we started talking about that ejaculation that was blocked. He said it was particularly enjoyable and seemed to last longer than the typical orgasm. I have experimented with blocked ejaculations a few times, and found the orgasms did last a bit longer than usual. I proposed that I might try something I have fantasized about, but would be too chicken to have it done to me. He is after all, more adventurous than I am, and does rather like the rough stuff. I said could bring him to orgasm, and hold it inside by squeezing the tip of his penis. Then, after he came, since he likes various forms of post-orgasm stimulation, I would try to milk him backward. Starting from the tip of his penis which would still be held closed, I'd squeeze farther and farther down his shaft, forcing the sperm backward. I'd continue pressing past his balls, down as far as I could reach to the base of his penis, even reaching my fingers into his asshole if necessary, until the ejaculate was squeezed all the way into his bladder. He was very enthusiastic about the idea. So, we proceeded. With this exciting new idea, he grew even harder, and came back to the brink of orgasm, where he had already been several times during the past hour. But this time, I kept going, and as his orgasm started, I did pinch the tip of his dick. But it was hard to get a good grip. My fingers wanted to slip off due to the oil we had been using. I tried to get a better grip without losing the grip I had. I didn't want any sperm to leak out. It seemed like his orgasm was lasting longer than usual, and sure enough, I just couldn't maintain a good grip between my thumb and the side of my forefinger, and a squirt of semen shot into the air. It was under pressure, so it shot a good three feet! I quickly got a better grip just below the tip with my other hand, and at that point, I noticed something quite weird: He was still orgasming and the contractions were very, very strong. It was quite obvious. I could feel his dick pulsing strongly in the one hand, and my other hand, which had been pressing lightly on the spot just ahead of his anus felt convulsions there too. I had placed my hand on that perineum area expressly for the purpose of feeling his pulsing orgasm, and was rewarded with some remarkably strong pulses. But not just a few. He kept going and going. I was quite surprised that he was still orgasming. As I was noticing all that, my grip was slipping again, and another squirt of sperm escaped, and shot well into the air again, landing in sprinkles against his stomach. WTF? He was still orgasming! I tried improving my grip, but didn't get it right, and yet another squirt slipped out. Finally, I got a good grip, and after what had been probably a full minute, his orgasmic contractions weakened and subsided. Needless to say, we were both quite amazed. I have had a lot of masturbatory experience in my life, and I've never seen anything like this. In all my experiences at the San Francisco Masturbate-A-Thon, SF Jacks, male tantric massages in Berkeley, the Power Exchange, and all sorts of experimentation with friends of both sexes, I have never seen a male orgasm last anywhere near as long as this one did, and have never seen such strong contractions. I don't know if it is something specific to my friend, or whether it could be like that for everyone who has an ejaculation blocked in just the right way. I certainly want to find out, and will be experimenting further. Unfortunately, I had lost a good bit of the sperm I had hoped to trap, but there was still some in his urethra. Perhaps if I had trapped it all, the orgasm would have lasted longer, and been even stronger. I started the process of squeezing it back toward his bladder, and did my best, squeezing down and down. Past his balls. Around the bottom area under his balls, and finally into his asshole. I don't really know whether I managed to actually move any sperm back or not. And don't yet know whether I was able to get anything actually into his bladder. I'm going to ask him next time I see him, probably in a few days. But better than that, I'm pretty sure he'll want to try again. This time, I'll make sure to get a better grip, so I can trap all the sperm, then there will be enough to tell for sure whether it is being forced back into his bladder. I might have him do it to me, too.