Butt Fucking
In the movie "Tokyo Decadence", there's a scene where a dom forces her dog to drink a hooker's urine from a bowl. She then proceeds to fuck his ass with a strap-on. These men wouldn't let another man do this. Nor would they allow a she-male. Not unless domination was involved. Being fucked by a dom is the ultimate submission. It's allowing the dom to treat him as a woman. Emasculated, the submission is complete. For more, go to http://fhg.slaveinpain.com/gal5/index.html