You can start slow. Begin by sucking his dick and getting his leaking pre-cum and your saliva coated mouth loaded up & then French kiss him. Tell him how hot and sexy it is to swallow cum, or at lease swap cum. A lot of guys have to go the three-some route in order to get a big mouthful of cum. Once he does swallow, you can tease him really hard by telling him he must love the taste of his own cum. And when is he going to graduate to sloppy seconds? Tell him you want to fuck other men while he watches you.