Anything on MDMA feels good, so of course sex would. That said, I definitely don't think it's the best. The difficulty getting hard & cumming are two negatives. Also, I have found that I often only remember bits & pieces from when I roll, particularly if I roll hard, and that is one reason I stopped doing it. What is the point of having the time of your life if you barely remember it?
A good alternative is methylone, which is like a lighter roll. If I had to nickname it, I'd call it "serenity" or something like that. Some find it disappointing because they want that super strong e-tard roll. But if you just accept the euphoria it provides, it is great, and you are not so burned out the next day, and I don't think it interferes w/ erection or orgasm much (probably a little since it acts similar to ecstasy, but not so much I noticed a problem).
Also, I've had better sex on psychedelics than mdma.
The most reliable sex drug is 2c-b. It is trippy but also euphoric, so nearly impossible to have bad trip, and also sensual, and I don't think it interferes with erection or orgasm.
One of the best, but not so reliable, is foxy or moxy. These tryptamines related to magic mushrooms primarily enhance the senses and drop filters we place on our senses, so you feel more of everything. No, not like ecstasy at all. Ecstasy does not make you feel more, but makes what you feel feel better. Foxy (and it's close cousin moxy) make you feel more, but that is not necessarily better. Sensory overload is possible, and feeling more but not necessarily better means you really need to be secure in having a positive set and setting. I've made the mistake trying it at a club and it was overwhelming, too much stimulation. But maybe it would have been okay with smaller dose. Anyway, if you get into sex on it, it is pretty awesome. One drawback, to me, is that it lasts like 8 hours, and these days I generally only have time / energy for shorter trips. A good substitute is 4-ho-dipt, which has a somewhat similar effect but lasts half as long. My last gf said the 4-ho-dipt made her climax much more easily, too, so that's a plus (ymmv).
Maybe the best sex I've had was on ketamine. I know, weird. I never thought of it as a sexy drug, it kind of makes everything seem alien or matrixy. But I found it can be amazing at lower doses for massage and yoga. I think of it like it puts to sleep some neurons, which has anesthetic effect, and the remaining awake neurons, being only a partial representation of your mind, have a different view of things, look at everything from bit different perspective. One aspect of this is that you can sometimes find you are very scattered, uncoordinated, clumsy. However, I have had just as many times when this left me much more focused, more mentally united, able to dive much deeper into meditative practices, able to go deeper in massage as I dove mentally more into it, and able to let anyone massaging me in deeper (maybe in part because the anesthetic qualities meant I felt less pain/discomfort). Similarly for yoga, if you don't get clumsy but get focused, you may find you can get deeper into poses, relax more, release more muscle tension to aid your stretch, etc. Anyway, I think the sexual enhancement is akin go the massage/yoga enhancement, you are much more focused, have sexual tunnel vision, which is very hot. One time I was on it, started making out with my ex, and felt I was merging with her on deeper level, had closed eye visuals of paradise type settings, was amazing, went on & on. But again it is not reliable to lead you to sexy place.
I've also had great sex on 4-aco-dmt, as I find this flavor of dmt to be very smooth / liquidy in its feel, kind of like acid. Not an out of body experience like smoking dmt. It is easy to steer to sensual place IMO. Along those lines, my last gf and I decided to smoke 5-meo-dmt for the first time, and I expected out of body hyperspace experience, but instead it was just very trippy but still very present, and we then had amazing trippy sex, and it only lasts like hour or two, so you can do it any night even when you have to get up early.
Combos are also fun, 2cb + 4-ho-dipt or 2cb + methylone or 2cb + ketamine + 5-meo-dmt. I think I've mixed and matched most combos (did not care for 2cb & foxy, maybe both too strong, clash, or just had off night). Of course, you probably also want to add weed, maybe some coke, as well as GHB if you have it (or maybe xanax if you don't). The G or Xanax help calm any anxiety, so they are good buffers when you take a psychedelic like foxy.
I've had very good sex on shrooms, but that is to me something it is tricky to steer into sensual place. Possible, but bit more challenging than others. Acid can be great for sex, but you also need to steer it, and, too, I just think it lasts too long for me.
~psychoblast~
