You're right...this is probably a subject best left alone. But, I can try to explain the rape fantasy for you so it will help you understand it more...I'm not the best with descriptions so bear with me.
The whole idea behind rape fantasy is that the woman who is having the fantasy is absolutely powerless against the person or people who are assaulting her. Becoming an unwilling slut at the mercy of others, basically. These women are completely thrilled by the fact that someone is using them in a sexual way and there's absolutely nothing they can do about it. As you can probably tell, it's a fantasy based on powerlessness...which, in turn, actually suggests that rape itself is an act of control and power. The fantasy would be useless without the sexual part, of course...no woman would be turned on by being powerless in a job situation, for example. Some women are just the opposite...they are thrilled by the prospect of having complete control and power over a person or even many people. But as double standards go, no one would think twice about this as some kind of "problem"...actually, they'd probably say "wow that woman is so strong! bravo!".
Rape fantasy and "no strings attached" sex are completely different. In "no strings attached" sex, both people are of equal say in the matter, and no one expects anything of the other except a chance to get off.
Oh and I should clarify one thing...there's a huge difference between a feminist and a militant feminist. Some people would claim me to be a feminist but I'm not...I'm actually an equalist.