Cartman's 'Muscleman Marc' doll is based on fashion designer Marc Jacobs, who has real life tattoos of Cartman's Clyde Frog and Rumpertumskin dolls. Jacobs commemorated the reference by getting a Muscleman Marc doll tattoo on his arm.
The episode is based on cut footage from the season 14 episode "201" in which Cartman holds a tea party with his stuffed animals, and discusses the identity of his father with his mother.