Bumping this old thread....
A lot of times, a simple "Please, Master, let your slut X (usually orgasm)." is all it takes. For him and me, it's to remind me that I have forfeited the right to orgasm without permission and he loves making me beg for it and degrading myself a little in the process before giving in. A few times when we both know I have done something naughty (such as play without permission) or neglect household chores or whatnot, he will make me beg not to get to cum since he may be in the mood to play with me and not allow me something. So the begging ends up more like, "I want to cum, but I am not deserving so please continue to use your slut and not allow me to." - if I sound pathetic enough in this situation, about half the time he'll give in and let me orgasm for being willing to beg him not to allow it.