You pick up a hitchhiker who is eternally grateful for you giving her a ride home. Once you get there, you ask her for money for the ride, and she panics, telling you she doesn't have any money on her. But you've already given her the ride, so she has to pay somehow before you'll let her in. You pull down your pants and tell her a blowjob will suffice, but when she asks if she's pleased you enough with her mouth to be able to go in, you tell her she needs to fuck you too. She doesn't want to as she doesn't have any protection, but it's the only way you'll let her go inside. She gives in and enjoys the feeling of your cock stuffing her in the backseat like a little whore, then thanks you for the ride again... even if she didn't know that that's what it would cost her.