These balls are called Ben Wa balls.
http://store.lovepotions.com/benwaballs.html
They claim to make a woman have a g stop orgasim just by her making the attempt to keep them in. They are not heavy as this advertisement claims , but they do fall out. I have not tried them as tiny metal balls in my pretty little space doesnt turn me on.....
Though, I am intrigued by the thought. I have heard some women who have used them and have claimed that they DO give and orgasim and quickly..
but.. in my experience, you can have an orgasim with little physical stimulation if your hold your PC muscles that hard ANYWAYS.
As for no physical stimulation and just fantasy... and women not being able to have an orgasim that way?
Uh.. ladies.. you can NOT tell me you have never had a wet dream.. you know.. where you wake up having an orgasim? ! There is no physcial stimulation there and it IS all visual.. so yeah, we can do it too. ;-)