You give him a blowjob.

"I'm going to suck you!" you say. You kneel down so that his penis is in line with your mouth. He shoves his dick through your lips and you begin to work him. You're slow at first, the only blowjobs you've ever seen having been on the web, all done by girls. Gradually you get into it, moving your head back and forth while moving your tongue around his shaft. You stop just before he was going to cum, wanting to make sure he stays fresh for the next part.