unfortunately, in many cases it might not be much different than a "prison rape" fantasy, but in this case it's being an inmates "bitch" as shown in this clip:
http://www.youtube.com/watch?v=TFN8dYgSRBk
Anyone who dresses voluntarily, this fantasy doesn't make much sense. However, the fantasy of being forced to be feminine and then forced to go out in public is an entirely different scenario since many of us fear that.