Marriage was never very successful for me maybe because since puberty I have had strong bisexual leanings. I have a younger half sister Beth who is pretty much in the same boat, divorced after only five years and living with female roommates mostly since. Last spring we got together and decided to join up, her lease in the city was up and she would come out to my house and become a commuter with me. That's the background for this story, afterall we are talking masturbation here and although new to this website I'm willing (eager!) To make my contribution. I have expressed my bi urges with first boys as one and then with adults as one. It's always been masturbation though (although extremely mutual and sperm sharing) and I had no MF experience at all.
That changed soon after Beth moved in. It was her 48th birthday and I had taken her to lunch which included a good bit of wine at a local club following a morning of golf. We got home around mid afternoon and were sitting around in golf shirts and shorts and I got a wave of overcoming horniness partly the wine and mostly no handjob for days. I got a hardon and couldn't resist a rub or two and Beth saw that and when I glanced at her she quickly diverted her eyes. Feeling a spontaneous impulse I said 'Do you masturbate?' and sheepishly she answered 'Yes'.'Ever together? 'Yes but only a female'. That broke the ice. It was chilly in the house and I went to my bedroom stripped naked and put on a bathrobe grabbed a towel and went back to the living room.
With out a word Beth got up and returned also in a robe. We sat in facing chairs and I opened my robe with my cock in its full hard curving slightly backward mode foreskin half back. Beth parted her gown exposing a large pubic triangle and still firm big nippled tits. Her bush was parted and the hair already wet around pertruding lips. Tomboyish still and lean and fit my little sister's big cunt looked as masturbate-conditioned as does my fat hooded cock. I got up and sat on the sofa working the foreskin over my bulging glans and she came over and sat beside me fingering her clit. I put my hand below hers and explored those prominant pussy lips. My fingers were wet with a pungent vagina smell which thrilled me as I smoothed the juice on my bared glans.
My usually steely control was giving way badly. I asked if she minded semen and she didn't reply. I stood up and kneeled on the sofa around her thighs and touched a grape-like nipple with the tip of my penis, fingered the foreskin hard back and my ejaculation exploded out in splats washing her tits with running sperm. Her body stiffened and her vagina gaped and came soaking both our pubes with sputtering juice. Once the masturbation initiation was past us, we openly talked of our interest in our own sex and how for each it was expressed only by masturbation. FF masturbation involves nipples a lot more than MM does and oral stimulation-sucking tits, is an important FF feature. Maybe eating pussy might fall in the the category FF (surely MF!). And on the MM side, why not oral, cock sucking? Guess my concept of same sex masturbation is still a work in progress. Any ideas, fellow masturbators?