For women only. I don't think men can do this.
Is it possible?
I think it is. Though it might not necessarily be very common.
This has never happened to me. I've experienced sensations without any stimulation, though not a full-blown orgasm. So I can see how it's possible.
From a more logical point of view (not based on my own subjective experience), I think orgasms and being stimulated is like...very mental for women. Like, a lot. We have to be in a certain frame of mind. If you combine that with having physical control and mastery over your body, like kegel exercises...then I do think it is possible to have an orgasm just by thinking about it.
What's the frame of mind we need to be in? I don't know. This isn't a science. But if you want to bring the emotional component into it (and if you read this blog, you'll know that I always emphasize the emotional component in sex/masturbating...because morally, all of this should be tied to love in some way)....I think it's about...getting yourself to feel what a man's love feels like. So, I don't know. Think up scenarios/stories in your head, think back to real experiences you've had, combine the two, whatever....it takes to get you feeling and imagining those things in that moment.
And use your kegel muscles!
And don't put too much pressure on yourself.
All of this goes for me, too.