I developed this masturbation/sex technique hmmm... yesterday.
What happens is that, when you have an orgasm, the muscles by your prostate contract, making you ejaculate. Notice, here, how an orgasm is not the same as ejaculating.
The technique is simple: you must be relaxed enough not to let your prostate muscles contract, allowing you to have an orgasm without ejaculating (which means the possibility of multiple orgasms as well)
When doing it, you must not bend your muscles the slightest (I mean the muscles in the pubic area, you may still use you hands/legs etc). Leave them completely relaxed and do not move them.
If you manage to do it properly, not only will you get an orgasm without ejaculation, but also th best masturbation/sex you've ever had. It will last longer (not only the orgasm, the whole thing) and it's pretty much more satisfying. It's like.. hard to explain... Aff just do it... but be sure it will take longer than usual, and the whole thing will be satisfying, not only the orgasm itself.
Guess I explained it properly. Any doubts, go ahead :P