That's quite enough of that. Let go and try and cum again.
Hmmm, what shall I have you do? How about just taking your palm, spitting on it once, and rubbing it against the very tip of your cockhead. Little circles. Keep that palm flat.
Can you cum for me? Can you make a big gooey mess right into your hand? Pleeeaaase? Really work for me, rub those circles as fast as you can. I know it's a little over sensitive, but if you can just bite your lip and bare it long enough maybe it will push you over.