The episode opens with a small crowd, including Wendy, Bebe, Jessie, and the other girls, gathered to see Paris Hilton make an appearance at the local mall. Wendy is rebuffed by her friends for not knowing who Hilton is. Hilton enters to the cheering crowd. Hilton presents herself as "totally spoiled and snobby" and "a whore", according to one of the onlookers. Hilton announces the opening of the store, Stupid Spoiled Whore in South Park. Hilton says that she's happy to be in Gouth Dark, not knowing where she is. The girls enter and discover, among other things, lewd clothing and a perfume titled "Skanque." Wendy is appalled by the blatant objectification of women. As Paris drives away in her limo, her small pet dog, using her chatter into a cell phone as a distraction, steals the limousine driver's gun and commits suicide. Paris shrieks that "another dog killed itself!" The limo driver himself appears less than surprised.
Later that day, Wendy goes over to a friend's house and is quickly confronted with the Stupid Spoiled Whore Video Playset, a partial reference to the Paris Hilton Sex Tape scandal that occurred several months prior. The kit takes jabs at Hilton by describing its contents as including "a night vision filter, fake money, losable cell phone, and 16 hits of ecstasy!" Horrified, Wendy makes her exit, leaving her friends to recreate Hilton's sex tape. Meanwhile, Hilton is in fits over the suicide of her dog, Tinkerbell. In her throes of sorrow, she sees Butters and wants him to be her replacement pet. Her driver tries to explain to her that she can't just take a child, but she throws a fit until she gets her way. She puts him in a bear costume and names him "Mr. Biggles."
Wendy tricks her father into going to the Stupid Spoiled Whore store by threatening to buy a thong in the hopes of using his status as an adult to get the store shut down. But while he is initially appalled at what is sold there, he is quickly manipulated by the overly sexual and slutty women into accepting the store and declaring that his trying to close it down made him oppressive to females, assuring Wendy he'll make her the "Stupidest, most spoiled whore of them all!" Bebe announces a "Stupid Spoiled Whore" party at her house. However, they refuse to invite Wendy, stating that due to her intellect and status as Class President, she is clearly not a whore. The girls, wearing skimpy outfits, begin to make make suggestive comments to the boys passing in the hallway as they invite them; the boys generally respond nervously, or not at all. The one exception is Cartman, who walks past them on purpose hoping for an invitation, but is ignored, and proceeds to flip each girl off individually.
At the same time, Butters introduces Paris Hilton to his parents; he thinks he is now Hilton's boyfriend, rather than her pet. Hilton offers his parents $200 million for Butters, who doesn't like the idea, but his parents insist on discussing it alone. She passes out on Butters's bed while the two of them wait for his parents' decision. Butters again shows his naivete by curiously poking at Hilton's vulva, believing it to be an animal that lives in her pants. His parents eventually show up to announce that they're rejecting the offer – but only because they want at least $250 million. They tell Butters that he needs to be able to match Hilton's offer himself if he wants to stay, and suggest he try coal mining, like his grandfather. However, he is unsuccessful. Upon seeing a photo album in Paris Hilton's limousine, he discovers that all Hilton's pets killed themselves: Tinkerbell, who shot himself with the limo driver's gun; Patches, a poodle who hung himself; Scrambles, a cat who slit his wrists in the bath; and Cuddles, a spaniel who committed ritual seppuku.
Although the party was supposed to be a time to get "whorish" with the boys, the boys seem to be far more terrified than titillated, and most are attempting to run away from the girls with even Clyde crying after being let out of the closet. Cartman attempts to dress up as stylishly as possible to as to sneak into the party, but is rebuffed. Meanwhile, Wendy seeks out help from Mr. Slave, the biggest whore she knows, to try to become like all the other girls. After explaining to Wendy that being a whore is something you're born with and that it can't be taught – nor should anyone want to learn it – he then rushes off to break up Bebe's sex party (much to the boys' relief, especially Stan's, who was being held down and forced to kiss Red, as well as Clyde who after playing 2 Minutes in the Closet was left in tears, while clutching his ass and muttering "Owie!"). Butters escapes from Paris Hilton's captivity, and runs into the party, where he runs into the closet, only to run out terrified as the girl inside apparently began coming onto him. Hilton, who is following him, appears just in time to hear Mr. Slave telling all the girls that being a whore is not an enjoyable life and that "Paris Hilton is a nobody. She may have money, but she's a thoughtless, talentless lowlife". The two then get into an argument over who is the bigger whore, which culminates in Paris challenging Mr. Slave to a Whore-Off.
Paris Hilton begins with a variety of lewd sex acts, finishing by stuffing an entire pineapple up her vagina. Mr. Slave counters by removing his pants, leaping into the air, jumping on top of Hilton, and jamming her entire body up his anus (to which Mr. Garrison smugly replies "Now that's a whore!") The crowd is amazed at this feat and applauds, but Mr. Slave silences them by telling them that he should not be applauded, because being a whore is a bad thing. He then delivers an impassioned speech explaining that young girls shouldn't dress whorishly and that parents need to teach their kids to have better role models than Paris Hilton; "If you don't teach your children that people like Paris Hilton are supposed to be despised, where are they going to learn it?" Bebe and the other girls seem to get the message (somewhat) and apologize to Wendy for having said that she wasn't stupid, selfish, or a whore. Butters is happy to have escaped living with Hilton, but now must face the wrath of his parents, who are upset about not getting $250 million. Although his mother didn't care about it, his father is still angered by this and grounds him. Meanwhile, inside Mr. Slave, Hilton meets the Frog King from the episode "The Death Camp of Tolerance", who sets her upon the same quest as Lemmiwinks. The "Ballad of Paris Hilton" is sung as Paris attempts to crawl through Mr. Slave's anal cavity, and continues over the credits.