Your hot trans step-sister, Melissa, is the black sheep out of the two of you... even though you're obviously the slacker loser, and she's the hot popular one. Despite the fact that she's in college, Melissa's always getting grounded, and her car keys confiscated, and she's here to give you an earful about just how fucking unfair that is!
Except this time... Melissa's got a plan. See, her room's next to yours, so she overhears your porn all the time, and she knows exactly what you're into... step-sisters... and trans girls. That's right. She knows you've got a thing for her. And she's dead-set on going to her friend's party this weekend. AND she knows you're a horny loser who'll do anything to see her tits... and her cock...
...and before you know it, you've handed over your car keys, and the title to your car, and promised to pay for her gas, you step-sister-loving gooner loser.
That's right, you're Melissa's little bitch now. And your reward for being a horny loser with no self-respect? A hot date with your own step-sister every night. Y'know. As long as you keep gassing up *her* car. Like a good boy.