馬什奶奶 is Randy Marsh and Jimbo Kern's mother as well as Stan and Shelly Marsh's paternal grandmother. She only made one on-screen appearance which was in "You Have 0 Friends", although she has been mentioned in dialog in other episodes.
When Stan's friends Cartman, Kyle and Kenny create a Facebook for him against his will, Stan begins to become assaulted by Facebook-type requests from everyone around him, including his grandmother. Apparently suffering from some sort of illness and hospitalized, Grandma Marsh spends much of her time on Facebook to keep in-contact with her family and friends. However when Stan does not immediately "friend" her, she contacts her son Randy who then demands that he pay attention to his grandma's Facebook status.
Later when Stan is literally 'sucked into' Facebook, a digital avatar of his Grandmother is seen interacting with all of his other Facebook friends, at a digital party created by his now sentient Facebook profile. Once Stan defeats his Facebook profile in a game of Yahtzee, she and everyone else on Stan's friends list are transferred to Kip Drordy.
Despite her failing health and the suggested age of Grandma Marsh, she appears to remain relatively younger than Marvin. She has grayish white hair and glasses. However due the fact that Grandma Marsh has only appeared as a digital avatar character in the techno-world of Facebook, her appearance may not exactly be accurate to her current state. Also she is not seen wearing normal attire, but instead she is seen wearing a Tron-like costume of glowing technology.
Grandma Marsh does not live with Stan's grandfather, Marvin Marsh, this would imply that she and Marvin are divorced.
- Grandma Marsh had both her sons by different men.
- Due to the fact that Jimbo Kern is 51 and Randy Marsh is 42, this would imply that her ex-husband Marvin is her second husband, assuming that she did indeed marry their fathers.
- Grandpa Marsh stated as being 102 years old, Grandma Marsh looks considerable younger than him. She was most likely much younger when they were married.
- "Quintuplets 2000" - Randy, "Everyone who has a Grandmother, step forward." [Stan and Cartman step forward, then the girls] after the Romanian Quints Grandmama dies. "Not so fast, girls".
- "Margaritaville" - Stan, "But Grandma said I could use this money to buy whatever I want". Grandma had given Stan a check for $100.
- "You Have 0 Friends" - First appearance and speaking role.
- "Hummels & Heroin" - Seen as a young woman in a photo in Marvin's room in Shady Acres.
- "Nobody Got Cereal?" - Marvin discusses having sex with her and "finishing" on her breasts to avoid pregnancy; Randy Marsh was conceived accidentally when Grandma put her finger up Marvin's butt, causing him to ejaculate early.