|Directed by:||John Holmquist|
|Written by:||Tom Devanney|
|Release date:||November 15, 2015|
Peter's Sister is the third Thanksgiving episode of Family Guy.
Lois returns from shopping for Thanksgiving and is not happy about the holiday due to lack of help from the Griffins. Meg brings in the mail which includes a letter from Peter's sister Karen, who the family has never heard about. Lois mentions they are estranged due to bad blood between the siblings. She writes that she is visiting for Thanksgiving because their mom Thelma has died and she has no one else to be with.
On Thanksgiving, the Griffin Family, Glenn Quagmire, the Brown Family, and the Swanson Family are enjoying the holiday while watching a "What we now know" version of The Cosby Show. When Karen arrives, the family except for Peter is happy to meet her as she greets him with a fart to the face like he does to Meg. Joe, Glenn, and Cleveland recognize her as professional wrestler "Heavy Flo." In the kitchen, Peter gripes about having his sister over with the way she treats him. During dinner, she embarrasses him further with stories of their youth and encroaches on his traditions. During a family football game, Karen nearly chokes Peter unconscious when she pulls her signature wrestling move on him.
Meg begins to see Karen for the bully that she is, as her antagonistic actions directed at Peter are similar to his targeted at Meg; since the reason for Peter's abuse is the abuse Karen gave him as a kid, Meg tells him he needs to address how Karen mistreats him. He resists because he is afraid of what she could do to him but he changes his mind when Meg tells him that it'll cause the abuse between the two parties to stop. Peter decides to become a lady wrestler to defeat Karen in the ring. Peter dons the disguise of "Maxie Patty" and gets training from Glenn Quagmire, Cleveland Brown, and Joe Swanson which turns out to be useless.
During one of her matches, Peter confronts his sister in his disguise and calls her out getting an invitation to face her. She immediately begins to wallop him but when he blurts out her name she is aware of who it is as they continue their match. But when Karen is about to break Peter's arms, Meg arrives in the wrestling alias of Teen Laqueefa and knocks Karen unconscious with a folding chair. She reveals herself to Peter and declares that she will always stand up for her dad as Peter apologizes for his treatment of her. After the fight, Stewie comes into the ring inside a limousine dressed as a pimp and has an African-American prostitute with him hoping to take over the show (as during the fight, Peter mentions that Stewie is next in line to be in charge of the show if he kicks the bucket). Then Stewie sees that Peter is alive and is disappointed.
At the Griffin home, Lois is concerned about Karen's well-being, as it was mentioned that fake folding chairs were used in wrestling matches and Meg hit Karen with a metal folding chair that put Karen into a coma. Peter assures her that she will be fine. Peter then gets a phone call from the doctor which contradicts his claim where it is stated that Karen needs an blood transfusion. Peter states to the doctor that he doesn't want to check to see if he is the same blood type as Karen and decides to leave Karen to her own devices.