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 name is exactly because she cannot fully understand him. Ms. Stevens tells Cartman that she plans on changing his negative attitude about the rainforest, knowing Cartman's reputation for bigotry in advance. Upon arriving, the children meet the Costa Rican President and do a preview dance routine, but Miss Stevens is dismayed by Kyle's apparent lack of coordination.
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 when he is eaten alive by a man-eating coral snake, even though "they're more scared of us than we are of them", Cartman infuriates the snake with his stick and narrowly escapes death by constriction. Miss Stevens and the children are scared and on their own in the jungle. 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 work--according to Kelly--because they live on other sides of the country. They run into a group of revolutionaries and try to recruit them to their cause, to which the rebel leader replies: "We're not getting gay with any kids" and have to run away when government troops arrive and start a battle. With the group still wandering aimlessly around the rainforest, Cartman deciding to leave "this hippie", walks off, and finds a friendly crew working on a deforestation project.
Back in San José, with the concert about an hour away from starting, 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, and sacrificing Miss Stevens. At this point; she finally changes her mind and decides the rainforest is not such a good place after all, just as Cartman and the construction workers arrive 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, but Miss Stevens and the children hated their time in the rainforest so much that they changed the lyrics to their song. This new version rebukes the rainforest instead of praising it. At the end of the episode, a fictional public service message is show which tells the viewer that multiple cancer-causing compounds come from the rainforest and that hundreds of people a year die as a result of it, urging them to help destroy rainforests around the world.