So if my previous posts weren't any indication, I'm absolutely in love with the idea of operant conditioning in various scenes. Operant conditioning can lead to the control of nearly any animal on the planet, including humans, and any will is apt to crumble and break under such training.
Now, usually this would be done with open communication of demands to the sub. Basically various nonverbal cues are pretty strong and consistent, but verbal cues are more precise. If you're required to acquire permission to service your Sir's boots before doing so, but he grabs your neck and forces you to the floor, usually it would be a verbal cue granting the permission.
As an extra mindfuck, I'd love to be dominated by someone who doesn't speak English during the scene. All of the sudden, that same situation suddenly goes an entirely new route. You find yourself on the floor, boots in your face, and Sir says something. Do you assume he's instructing you to lick them? Is he telling you to be still? Is it some off-handed comment as to how worthless you are?
And suddenly we have it: damned if you do, damned if you don't. Depending on how broad the commands range, you could pick up a decent chunk of the language. Suck it, Rosetta Stone.