My mom told my step dad that he wasn’t allowed to fuck her up the butt. In order to make him feel better she offered that he could fuck her daughters’ asses whenever he wanted, as long as she got to watch.
Now every time he calls my sister to his room, she knows that her asshole is about to get fucked. She never knows when he’s gunna want it, but when he does, she does whatever she can to make him cum quicker so the pounding will stop. Even if that means resting her pretty feet his balls, while his big dick stretches out her cute little anus.