"Rainforest Shmainforest" is the first episode of Season Three, and the 32nd overall episode of South Park. It originally aired on April 7, 1999.
The boys are recruited to a rainforest-saving choir by Mr. Mackey after showing poor behavior. Unfortunately for them, the group gets lost in the forest.
Ms. Stevens is in Mr. Garrison's class recruiting students for a rainforest saving choir tour called "Getting Gay With Kids". All of the students are uninterested except Kenny who falls for one of the girls in the choir named Kelly. Cartman doubts whether Kyle is the suitable person for the choir due to his usual bigotry against Jews, claiming that Jewish people don't have any rhythm. Kyle in return yells "Shut up fatass! " at Cartman, Stan simply says that choirs suck. Mr. Garrison rebukes the boys for their poor behaviors but Cartman still refers to information packets as toilet paper. Mr. Garrison has no choice but to send the boys to Mr. Mackey's office.
The boys enter Mr. Mackey's room after Craig, who has just been sent out for flipping off Mr. Mackey several times. As a punishment and a way to educate the boys, Mr. Mackey decides to sign them up for the choir tour, which delights Kenny but upsets Stan, Kyle and Cartman, who don't even care about the rainforest.
The children are on their way to San José, Costa Rica. Kenny sits next to Kelly on the bus, and Kelly calls him Lenny, Benny, Johnny, and pretty much any other name that sounds similar to Kenny, because she is not sure what his real names is due to Kenny's muffled speaking. Ms. Stevens tells Cartman that she plans on changing his negative attitude about the rainforest, knowing Cartman's reputation for bigotry in advance. They learn the choreography during the trip. Upon arriving, Eric Cartman finds out that Costa Rica is a very poor country, then he provokes the country as well as its people like he always does. Ms. Stevens manages to keep Cartman's trouble-making mouth shut by promising him some ice creams.
The children meet the Costa Rican President who doesn't understand English, until Mr. Mackey comes and makes it clear. They do a preview dance routine outside the Capitol Building, during which Kyle is apparently off the beat, making Miss Stevens dismayed. Local people however pay no attention to this event.
On their tour of the Rainforest, the children see the 'wonders' of the Rainforest (all of which Cartman hits with a stick to "assert his authoritah"). Then their tour guide is killed and is eaten alive by a man-eating coral snake, even though he happens to be explaining that "they're more scared of us than we are of them". Cartman infuriates the snake with his stick and narrowly escapes death by constriction.
The accident leaves Miss Stevens and the children on their own in the jungle, totally scared. Kenny takes advantage of this by being supportive and protective to Kelly, which successfully earns her affection. In spite of this, their relationship wouldn't last long, according to Kelly, because they live on opposite sides of the country. The night falls with a terrible thunderstorm, Tony Danza shows up suddenly between Miss Stevens and Kelly.
On the next day, Mr. Mackey and the president of Costa Rica both discover that the choir group has never returned to hotel and they become pretty concerned. Meanwhile in the rainforest, a giant insect lands on Miss Stevens' back, painstakingly she gets it off. Then they run into a group of revolutionaries and try to ask for help, by giving "a gift of song", to which the rebel leader replies: "We're not getting gay with any kids", then he threatens to kill them because he hates Americans. When he is just about to do it, government troops arrive and start a battle, during which Miss Stevens and the children narrowly escape. As the group get back to wandering aimlessly around the rainforest, Cartman decides to leave this "stupid hippie activist", walks off, and finds himself a friendly crew working on a deforestation project. He demands medium spicy chicken wings for food at once.
Back in San José, with the concert about an hour away from starting and the kids still not showing up, the President stalls for time by telling Polack jokes. Meanwhile, Miss Stevens and the remaining children find The Yamagampa Tribe that intend upon killing them. They try to run away but get caught in quicksand, thus being captured and then taken to a Yamagampa village, where the Yamagampas plan to sacrifice Miss Stevens. At this point; she finally changes her mind and believes that the rainforest is a horrible place after all. Cartman and the construction workers arrive just in time to save everyone.
As they make their way back to San José; Kelly finally decides to become Kenny's girlfriend, even if they live far away from each other, which Kenny is happy to hear. Just then he is struck and killed by a bolt of lightning. Kyle and Stan say their usual lines, but when Kelly asks them who "they" are, since Kenny was killed by lightning, not people, Kyle and Stan are unable to answer her, claiming: "You know, They. They're bastards." Kelly then performs CPR and successfully saves Kenny, to the amazement of Stan and Kyle.
The group makes it to San José and perform their song. Since Miss Stevens and the children hated their time in the rainforest so much they changed the lyrics to their song. This new version rebukes the rainforest instead of praising it, and is considered inspiring by some of the audience. At the end of the episode, a fictional public service message is shown, which tells the viewers that multiple cancer-causing compounds come from the rainforest and that hundreds of people die as a result of it every year, urging the viewers to help destroy rainforests around the world.