I've heard of women who have a condition where they feel they're always on the brink of orgasm. So much so that it ruins their lives. And often their sex lives. The need to masturbate is unbearable for them. And they can orgasm through very little stimulation, even just a bumpy bus or a knock in that area.
I have experienced something like a phantom orgasm when I was sexting a guy and I felt really horny and I kind of felt a weird cramp and a rush of endorphins, as if post sex. Very odd. Only happened the once though.