Another male contribution, i'm afraid.

One girl i had a wonderful relationship with could do this and boy its amazing. She could have wonderful multiple orgams through vaginal fisting and or stimulation of her g-spot with two fingers (look in any good sex manual). Lying on her back was how she felt best. Her pussy would spasm so much i couldn't move my hand, then a torent of iquid would come down it - as sweet as her piss (we were also into watersports) yet as beatiful as honey. I used to get right in close and i can confirm this was from her pussy and not her pee-hole. It was agood ten mills / 10CC each time and she could on doing this so much the only time we'd stop was to change the sheets. Alas no other lady i've known has come in this way, but if they can , wow.