I just answered this question in another forum, so I shall simply cut and paste...
I've had many unspeakably beautiful experiences with my g/friend, sex, and psychedelics. Unfortunately, words to describe the moments of unabashed beauty and intimacy that I have experienced in conjunction with psychedelics and sex are very had to come by.
I'm lucky enough to have a g/friend who likes to explore her mind with psychedelic drugs (time permitting) almost as much as I do, so sex is a pretty big part of the tripping experience with us. Unless we are with other people, making love tends to take up a major chuck of the psychedelic experience (that is dose dependent though) when we take these things together. Sometimes we even have what we call sex trips: that is we take a low dose of a psychedelic for the specific purpose of enjoying each other's bodies with the enhanced sensations from whatever we took.
For me, orgasm goes to the back of my mind. If it happens, great...but it's not my main concern. My main focus is pleasuring my partner and transferring my feelings of love for her into acts of the physical, or enjoying the experience of receiving the same from her. Watching her smile, looking into through her eyes and into her soul has literally brought me to tears before. I'll never forget one delightful moment on a 2C-I/MDMA combo last year when I looked into her eyes, which were decorated with multi-colors while golden light danced around her, and I said, "I am making love to you and putting all my feelings and emotions into it, and it still can't even begin to get the point across of how much I love you."
The degree of connection and intimacy a psychedelic experience can inspire between a couple is startling. Of course a lot of this has to do with how close the two are in general. I've been with my g/friend for many, many years now so we feel very close to each other, psychedelic or no psychedelic. I don't know if I would feel so comfortable taking a psychedelic and having sex with only a casual girlfriend because I feel my most revealed and exposed (both mentally and physically) when I am naked and tripping. Wonder why?
As far as specific substances, I can't say any in particular are 'better' sex drugs than others. Off the top of my head.... I don't think there is one psychedelic I've taken that I didn't have sex on at one time or another, so I have a pretty good consensus as to how I feel on them all. I think it just comes down to set and setting.
In some aspects, I'd say psychedelic phenethylamines and entactogens might make better substances for erotic enhancement because of the relatively 'clear head' one retains while on them. LSD can make for some beautiful sexual experiences, but it is almost impossible to engage in such acts during the peak of a powerful acid trip.
As far as other entheogens...
Pot is NOT a sex drug for me anymore, though it may have been when I was younger. I tend to start focusing too hard on things, and sometimes I even get self-conscious for some reason. That, and the dry mouth, doesn't make for a sexy time.
Ketamine is not a sex drug by any stretch of the imagination, but once after a powerful ketamine experience with my g/friend, in which our love for each other seemed to be a significant theme of the trip, we had a powerful sexual experience. Although it was sloppy, and impossible for me to finish, I remember it as being one of the more beautiful moments I have spent with her in my life. We were both quite surprised, never thinking such things were possible on ketamine.
