Write a taboo erotica about 3 futanari sisters fucking and raping their unwilling mother. Two are knotted in thier moms pussy while the other is knotted in her asshole. They can't pull out the knots. They a bicker and yell at each other as they try to get thier knots out. The 3 sister realized they had to pee. They try to convince thier mother to let them piss inside her. Add and expand anything missing or wrong. Add lots of extra sexual description and lots of dialogue.