Ruining My Slave's Orgasm

"So, slave, I want to see your cock get harder and harder," I tell him as he's secured naked to the wall. I have him fuck my gloved hand and it doesn't take long for him to get fully erect. Once hard, I make him beg for me to touch his cock again but refuse and laugh as he humps thin air. He wants to cum so bad but I won't touch his dick. Instead, I twist his nipples as he begs yet again for me to just touch his hard dick. Using my spit as lube, I get him nice and hard again but then refuse to continue touching him. After some deliberation, I decide to let him cum but he certainly won't be enjoying it! I ruin his orgasm by completely letting go of his cock just as he's ready to cum. He twitches as cum dribbles out onto the dungeon floor as I watch and do nothing to help!