Dominating your Man: An Introduction
Let your poor little fuck toy know that you think he's had enough. (read all of this page before you start)
Without warning, go down on him and start sucking his balls. They should be VERY tender, as they are about to burst. Start working his cock with your mouth, and be rough with your hands. Spank him, tug his nipples, play with his asshole. Make the build up excruciating.
Tell him how much you want his cum, how you want him to blow it in your mouth, and how you can't wait to feed it to him. Ask him if he'd like that: for you to spit his load into his mouth and swallow it. If he says no, then tell him that's fine, and that he doesn't have to cum. You'll just suck him off until you're tired, but he has to hold his cum in. Also remind him that any unauthorized orgasms will be ruined and fed to him. He should understand his predicament pretty quickly...
If, on the other hand, he proves more receptive to it, then make him beg for it. Tell him you need to hear how badly he wants it, make him describe it in detail. Force him to build the image in his head.
When he gets to the edge and asks to cum, start squeezing and tugging his balls. Tell him to do it, and let him explode in your mouth. Gather every drop of his cum, crawl up to his head, squeeze his cheeks to open, drop that load into his mouth, and kiss him deeply. Share it with him, and once you're done, tell him to swallow it.