"Big Man on Hippocampus" is the tenth episode of the eighth season of the American animated sitcom Family Guy. It originally aired on Fox in the United States on January 3, 2010. The episode features Peter after he suddenly begins suffering from amnesia, and can no longer remember anything about his life, including his own family and friends. His wife, Lois, then attempts to reintroduce Peter to his surroundings, but he soon discovers partying, and having sex with other women is much more entertaining. Frustrated, Lois decides to leave her husband, causing her neighbor, Quagmire, to attempt to win her over.

The episode was written by Brian Scully and directed by Dominic Bianchi. It received generally negative reviews from critics, despite its "promising start," as well as its many cultural references. According to the Nielsen ratings, it was viewed in 8.1 million homes in its original airing. The episode featured guest performances by Dwayne Johnson, Adrianne Palicki, and Rick Pasqualone, along with several recurring guest voice actors for the series. "Big Man on Hippocampus" was released on DVD along with ten other episodes from the season on December 13, 2011.

The episode opens with the Griffin family watching television. A commercial for local auditions of the syndicated game show Family Feud is shown, prompting them to try out the next day. The Griffins are chosen for the show and reach the final round. During a fight with Richard Dawson about welching on the prize money, Peter hits his head. This causes him to forget everything about his life, including his family and friends. Lois tries to jog his memory by reintroducing him to his old self, including his children and his sex life. Unfortunately, this causes Peter to believe that he's free to have sexual relations with others in his newfound "bachelorhood." Lois had earlier told him that it is inappropriate to have sex with his children - in response, Meg attempts an incest joke ("Well, I wish you would've told him that BEFORE he lost his memory!"). Most of the family lambaste her for this and Chris kicks her out of the room. Deeply angered, Lois decides to move out, taking the kids. When Quagmire finds out, he jumps on the opportunity to pursue a relationship with Lois.

...
Wikipedia