I can actually do this. Requires immense koncentration though. I fantisize on things that REALLY turn me on and focus 100% on the memory of the sensation of my penis going into a mouth/vagina/ass, how every stroke feels. I kind of "hump" with my pelvic muscles. Tightening/realeasing at the same speed as my fantasy. It helps to go as long as possible without cumming/sexual stimulation. The orgasm is usually enormous and leaves me exhausted. It's the only tine i cum by myself that my breathing changes into how it normally gets after good regular sex. Orgasms are mostly mental, belive it or not. Which is why It's way easier to get a girl to cum when she's in a good mindspace and comfortable. If I want my fiancé to cum i make sure there is nothing on her mind stressing her out and take a good amount of time working up to it. If you want to cum by yourself wotjout touch you kind of have to find your mental sexual stimulation buttom. Like If you really know what you like and get a horny sensation from thinking about it, abuse that sensation. Force it over and over again until you get real riled up. If you desperatly want to touch to could push your hands around your gender to help out. I doubt i could still do it today though since i have regular sex. Maybe i could do no touch together with wifey..? Dunno. You have to be really fucking horny and know how to get even more horny. Takes a good 30-40min to pull off.