An Elephant Makes Love to a Pig is episode 5 of Comedy Central's series South Park. It originally aired on September 10, 1997. South Park's creators, Trey Parker and Matt Stone, refer to it as "An Elephant Fucks a Pig" on the Season 1 DVD.
Kyle's mom won't let him keep his new pet, an elephant because it's so huge. So the boys turn to the Dr. Mephisto to genetically engineer a smaller elephant.
The boys are waiting at the bus stop when Cartman notices Stan has a black eye. As it turns out, his sister Shelley has been beating him up and he doesn’t know what to do. Kyle has problems of his own, as his mom won’t let him keep his new pet elephant (that he got from mail order from Africa) in the house. At school, Mr. Hat teaches the class about genetic engineering, which prompts Kyle to decide to splice his elephant with Cartman’s pot-bellied pig, Fluffy, to make little "pot-bellied elephants". Upon hearing this Terrance bets Kyle that he can clone a whole person before Kyle can get a pot-bellied elephant. Thus, the cloning war begins.
Mr. Garrison suggests the boys use their genetic modifications for the upcoming science fair and that Kyle and crew should check out the genetic engineering ranch outside of town. Mr. Garrison then asks Stan to stay after class talk to about his black eye. When Stan explains that bruise is from his sister Mr. Garrison calls him a pansy and sends him home. Once at home, Shelley again beats up Stan and throws him out the window, where the guys are waiting for him. They head off for the South Park Genetic Engineering Ranch. While at the ranch, Dr. Mephisto shows them his genetically engineered collection, including several monkeys with multiple asses. Mephisto then explains that, just like the Loverboy song says, "pig and elephant DNA just won’t splice." He then steals a blood sample from Stan and the boys flee.
Back at school the boys learn Terrance has cloned a human foot. The boys go to Chef with their genetic engineering problem, and after he too cites the Loverboy song, he gives them the idea to try to have the animals "make sweet love" to breed. Stan goes home and gets beaten up by Shelley again. Meanwhile, back at the ranch, Mephisto and his assistant have created a human clone of Stan for Terrance (Mephisto’s son)'s science project. The boys attempt to get the pig and the elephant drunk to get them to make sweet love, but it doesn’t seem to be working until Chef stops by and sings to the animals with a little help from Elton John.
The cloned Stan breaks free from Mephisto's ranch and proceeds to terrorize the town. The boys eventually find the clone and take it to Stan’s house and convince it to attack Shelley, which it does after destroying the house and indirectly killing Kenny. Mephisto shows up and kills the clone, but Stan is afraid he’ll be in trouble for everything the clone did, but Shelley, in a brief moment of kindness, takes the heat (after which she beats up Stan again). When the science projects are due Terrance presents a five assed monkey, but Kyle has nothing until the pig gives birth to a pot-bellied pig that looks like Mr. Garrison. Garrison quickly awards it first prize over Terrance's five-assed monkey.