Dorm mates

You maneuver yourself so you could get in there. You then start with his balls, massaging them gently as you grin at him. You keep going at them for a while, then you move up to his hard ass cock. You rub it up and down slowly at first, then you speed up and he starts cumming on your hand. His cock softens a little and you think it’s time to try something to harden it up again. What will you do?