I watched one gay porn film time ago that involved a man with vagina. It was a surprise, because the whole film was rather rough, with big, muscular guys fucking. I don't remember well that film, but I think that one of the guys unzip his trousers, and started fucking another guy. When the camera showed a close-up, it was in fact a penis-shaped dildo. The other guys discovered it, removed the dildo and the guy had a vagina, so they fucked him instead.
I think that the whole film happened in a circus or something like that. May be this rings a bell or helps you with Google…
[5 minutes later]
Ok, here it is. "Cirque noir" from Titan Media. hxxp://www.hisxpress.com/cirque-noir-directors-edit.html . Unfortunately, it is banned in GT so you will have to find it somewhere else.
Enjoy!