Donald was confused, his sister had a letter from school informing his mother that he had failed a subject. A subject from last semester in which he scored an 'A'.
Jill comes home to find her brother and her cousins having sex. When sneaking into her room she discovers their parent having swinging sex and acting out fantasies. She plans a birthday party for her dad where he takes her virginity thinking she is someone else.
A brother is tired of his overly smart but helpless sister. With their parents gone on a trip he discovers her new capabilities. He experiments on her to find out how her brain and body truly interact.
At a farewell party for Joey, the six friends and their many exes and lovers become much more intimate together with help from a special amulet owned by Phoebe. Their lives will never be the same.