I tried some tantric sex after reading Osho's meditation books.
I did YabYum with my girlfriend that time. We were sitting in union in this pose. After a period of time I got a feeling like a constant flow of energy into her Yoni, feeling like a continuous ejaculation.
She had some funny experiences as well as this sex is combined with meditation.
At an other time we tried having sex remaining at level 5 if level 10 is orgasm with ejaculation (can also be found in Osho's books). I loved it, as sex becomes very relaxed and heart-centered and unifying. Orgasm becomes meaningless, it's just a flow of energies, a state, being.