"Cartman's Mom Is Still a Dirty Slut" is the second episode of Season Two, and the 15th overall episode of South Park. It originally aired on April 22, 1998.
Just as Mephesto is about to reveal the identity of Eric Cartman's father, the genetic engineer is shot by a mysterious gunman. While the boys wait for Mephesto to regain consciousness, a blizzard hits South Park and the citizens are stranded for hours on end without food.
Right as Dr. Mephesto is about to announce who Cartman's father is, Kenny miraculously reappears (after having died in the first episode). The electricity goes out, the room is darkened, and two gunshots are fired. As the lights come back on, everyone discovers that Mephesto was shot. Chef feels his pulse, sees that he is still alive and rushes him to the hospital.
Upon entering the hospital, they meet Dr. Doctor, and Nurse Goodley, a nurse with no arms; they are the only ones working in the hospital. Meanwhile, back in town, the America's Most Wanted crew shows up, wanting to base an episode on Mephesto's shooting mystery. They run through auditions for Mephesto, Chef, Officer Barbrady, Mr. Garrison, and Kevin to play out a reenactment.
In the hospital, the doctor finally manages to get Mephesto on a life support system, but has many other patients to tend to. Outside, a terrible snowstorm brews, preventing any other doctors from driving to the hospital, so the doctor along with the nurse have to help everybody.
When shooting the reenactment for the TV show, a tree falls on the power line and the power goes out, so all the adults are stuck in a little building until the storm lets up. After only a few minutes, Jimbo comes up with the reckless solution of cannibalism in order to stay alive, since no one has had any food in hours (even though people tend to resort to this after a matter of days not hours. They choose to eat Eric Roberts first, who played Kevin in the re-enactment. Then almost as soon as they finish him off the residents remark that they're famished and haven't eaten in a long time regardless of the bones they 'just' finished picking. They eat the rest of the production crew (who in fact opposed the very idea).
Back in the hospital, the power goes out, so they have to come up with a plan to put it back on. The doctor suggests that they all switch into two teams: Team A and Team B.
TEAM A: Eric, Stan, Kyle, Chef, the doctor, and Nurse Goodley
TEAM B: Kenny
Team B's job was to go out and reconnect the generator, while Team A's job was to go upstairs to a lounge, watch television, and drink hot cocoa. Unfortunately, the trip to the generator involves first wading through a sewer, and then going outside, fending off any velociraptors that may attack. Kenny later learns that there is a nice heated path to the generator, but only after arriving. Once Kenny got to the generator, he discovered there was no wire connecting the cords, so he decided to make the connection himself to restore the electricity, electrocuting himself in the process.
Thanks to Kenny, the power is back on so Mephesto can survive. At the closing of the episode, Mephesto gathers with everyone in the emergency room to finally reveal Eric Cartman's father. The answer: Mrs. Cartman.
Explanation? Mrs. Cartman is a hermaphrodite, meaning she has both male and female genitals. She actually ended up getting another woman pregnant, who gave birth to Cartman, which arose the final question: Who is Cartman's Mother? Is it Mrs. Crabtree, Sheila Broflovski, Mayor McDaniels? Cartman however, exasperated by the events of this episode and the fact that the narrator has been constantly asking questions throughout the episode, refuses to pursue the issue further, and says, "OH FORGET IT!"
In the South Park episode "200", it is revealed that Liane Cartman is, indeed, notEric's father. Eric is told of this by Mitch Conner, and then goes to see Mr. Garrison. When Mr. Garrison tries to deny it, Eric forces him to take out Mr. Hat. After a conversation between Conner and Mr. Hat, Mr. Garrison reveals that the DNA test was tampered with, and that Eric's father was present in the room that day. The episode ends before it can be revealed who the real father is.
In the next episode, "201", it is revealed that Eric Cartman's father is actually Scott Tenorman's father, Jack Tenorman. The identity was concealed because the Bronco's were having a great season, and it is implied that they were afraid that the revelation would cause a scandal. The result is that Eric Cartman is half-ginger and that he had his father killed and made into chili that he fed to his half-brother in "Scott Tenorman Must Die".