Weighing in from the "victim's" side of the issue, I would have to say that this can be a rather disturbing fantasy to have.

As one with submissive tendencies, I am aroused by the idea that I'm not the one in control and that the person I'm with might choose to make me do something that I don't want to do. Needless to say, you must trust your partner implicitly before you give them that much power over you.

As mentioned, it is imperative that during any sort of game you have a safeword. I've heard many horror stories from people who had never even heard of the concept of a safeword and got into a game that turned ugly. I cannot stress this enough. And if you're going to be doing something where one partner is likely to be gagged or is supposed to refrain from any speech (such as ponyplay) then you should have some pre-arranged signal, such as knocking a certain way, or a certain position.

I have had many discussions with people on the Dominate side of rape fantasy, but found few others on the submissive side. I know that I will never do this sort of thing as I have a fear of losing control that goes as far as being a true phobia, which may explain my desire to flirt with this sort of experience. I also, although married, have yet to meet anyone with whom I would place such trust as to allow them to stage even a mock attack upon my person and psyche.
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As an addendum, noting other comments: I'm my case, it is not a matter of repression. I just have a preference for something a bit on the dangerous side. I'm an adrenaline junky. I like wild roller coasters, too.