By this time, you need to get into a position in which you can bring your breasts into contact with his cock. Swirl his cockhead around and around the areola on one breast before finally touching the nipple in the center. Repeat this process with the other breast. As you do so, be sure to vocalize your pleasure at the touch of his penis to your tits with little sighs and moans.
Say: “I wonder what will happen when I rub your cock on my titties? Does it make you get even harder? Will you cum if I keep it up? I don’t think so. I think you’ll just have to lie back and enjoy it as I drag your straining cock across my nipple. Oooo! That tickles!”