Believing that Bill is a bad influence on Peter, Lois goes to confront Bill, but ends up having sex with him. Devastated about the incident, Peter leaves Lois and stays at Quagmire's house. Lois is wracked with guilt and visits him, telling him that the only way to mend their relationship is if Peter sleeps with someone else. Though uncertain that it will work, Peter chooses to sleep with Barbara Pewterschmidt, Lois' mother. Barbara turns out to be more than willing, but Peter bails out at the last moment and vows to Lois that he will never sleep with anyone else and they forgive each other. Peter goes to Bill to end their friendship, only to end up having sex with him, inadvertently getting even with Lois.