" So today we are going to improve your self control, or rather your ability to keep yourself from cumming."
She undoes one of your handcuffs.
"Of course you are doing the stroking, did you really thing your cock would be worthy enough to be touched by my hand ?
So the rules are quite simple, you do what I say, when I say it. And don't you dare to cum without my permission. If it should happen that you can't control yourself then ruin your orgasm and then lock yourself up in chastity for a week. Then come back here.
But that won't happen, right ?
Good.
Now grab that cock and get it hard"