Femdom tease, Ruined orgasm for couples.
Have him lay down and tie him spread eagle.
Climb on top of him, making sure to remind him of your deal, ask him if he's going to be a good cum slut and swallow everything!
When he says yes, laugh and say "See, you could have have said no and got out of it, you must REALLY want to swallow cum!"
Grab his balls, giving them a light squeeze, and comment about how full of cum they must be, and what a huge load he's going to have to swallow.
Slide down his body, kissing and licking his neck, and chest, stopping to bite his nipples, and working your way down to shaft and balls.
Kiss your way around his shaft, and lightly kiss his shaft head.
Ask him if it feels good.
Ask him if he wants you to suck his cock deep into your throat.
Tell him that you would love to feel him explode in your throat, but HE wanted something else! Laugh at that.
Tease him some more, have another orgasm, just make sure you keep teasing him physically and verbally!