After fucking my slave in the ass (Your Ass is Mine), his cock is twitching and he's begging for release. The rule with my slaves remains: if you want to cum, you'll have to clean it up.
I have discovered that the secret to getting a boy to consume his own cum is to A) be there and force it down his throat or B) get him so aroused that he'll agree to anything. Since you're sitting there with your cock in hand, we'll have to use the latter.