Do you think you deserve to cum today? How long has it been since your last orgasm? Answer honestly now.
Only that long? Next session we'll take that dry time and double it. At LEAST. I can't have boys casually strolling in here, not caring about whether they cum or not. If you come to me to ask for orgasm, you had better mean it with a burning desire from both the bottom of your heart and the depths of your swollen, aching balls.