Create a sexually explicit sex story about two twin sisters NAME_1 and NAME_2. Amyis a futanari with a dog cock. NAME_1 comes from behind lifts NAME_2's skirt while she lays on the couch. They verbally fight as NAME_1 slides NAME_2's panties to the side ramming her dog cock in to her sisters cunt. NAME_1 knots NAME_2's pussy. They physically fight. NAME_1 coats NAME_2's pussy with her seed. She love  this while NAME_2 is angry and furious and does nothing but resist. They find that they can't get the knot out. NAME_2 is horrified and try to pull her sister out of her cum soaked cunt but can't.  NAME_1 enjoys NAME_2's panic. She pumps more of her seed in to her sister. They continue to physical hit and punch each other while knotted till their parents come home to the incestuous scene. Include sexually charged dialogue. And write about the intricate sex the sisters have with impeccable descriptions.