STOP!
*grins*
Oh my, your cock was really just about to cum, wasn't it? It's a good thing you stopped. What's that? Oh...yeah I suppose that must have felt like a brick dropped on your balls, but at least the cum is safe where it should be.
Well, enough about your cock, and more about me. A promise is a promise. You can have as much of me as you want. Just crawl over to me and press your mouth against my pussy. And lick.
When I've had my cum, and you've had your fill of me, you may stop. I'll want to see those hands on the desk, I wouldn't want you losing any concentration on me.