The episode begins with Wendy doing her presentation of breast cancer awareness, which Cartman mocks. Mr. Garrison does nothing to stop him, having completely given up trying to control him. When Cartman continues jeering Wendy after class, she threatens to beat him up after school. Butters rallies his classmates, including Bebe, who alerts her peers in the girls' bathroom, Ike reports the kindergarten students, and Red tells the Goth Kids about it as well.
Anxious over that he might get beaten up and called a "faggot" by his peers, Cartman tries to cajole calling off the fight with Wendy, by apologizing to her. However, she refuses to reconcile unless Cartman apologizes publicly. He pulls her aside into a janitor's closet and tries to call off the fight with apologies, bribery, and desperate claims. Wendy then angrily tells him that there is nothing he can do to stop the fight and threatens "I will shove your ass down your throat and make you eat your underwear!". He painfully chokes down his underwear in an attempt to appease her, but this only disgusts and angers her.
Growing more desperate, he tries to convince Stan to talk her out of it, lying to Stan (and his peers) that she's trying to get out of it (pausing briefly to choke the underwear up and then nonchalantly pull it from his throat, muttering "Oh, that's where I put those."). When Stan says he can't do anything, Cartman angrily calls him a pussy and runs away.
At the end of the day, Clyde informs Butters that he'll miss the fight due to detention. Hearing this, Cartman runs and defecates on Mr. Garrison's desk, earning him a detention and a ticket out of the fight. During detention with Mr. Mackey, Cartman meets Butters, Craig, and Jimmy, who tells him there are rumors that he got detention to dodge the fight. He says he crapped on Mr. Garrison's desk because he is "hardcore", and Wendy tells Eric through the window that the fight has been rescheduled for tomorrow morning.
Later. Wendy is called downstairs by her angry parents. where she incredulously finds Cartman in her living room. sobbing into his mother's blouse and stating that he is being threatened and bullied at school. Wendy is reprimanded by her parents and forced to promise she won't fight Cartman. As her parents apologize to Mrs. Cartman. the derisive Cartman taunts Wendy while the adults' backs are turned. confirming that he was really faking. The next morning. when Wendy refuses to fight. Cartman continues provoke her. knowing he is safe.
Cartman revels in this victory and reads a "report" in class about breast cancer, laughing along the way and telling corny breast cancer-related jokes to jeer her for losing against him. Wendy loses her temper and nearly fights him in class when she is called to the office by Principal Victoria. Wendy believes that she's in trouble, but when she arrives, Principal Victoria congratulates her on raising awareness for Breast Cancer and then tells her that she has heard that Wendy is planning to fight Cartman for making fun of it. However, Wendy informs her that there will not be a fight to which Victoria replies "Oh no?" She then reveals to Wendy that she is a breast cancer survivor and that she personally learned that cancer is "pure evil" and cannot be reasoned with, and that one must risk everything fighting the "fat little lump" before it takes everything. Wendy quickly catches on, realizing that the principal is not talking about cancer, but telling her that she has to fight Cartman, regardless of the consequences.
Bebe spreads the word that Wendy is going to fight, and the entire school rushes outside. The vengeful Wendy arrives on the playground, confronts Cartman. When he threatens to tattle again, she tells him that she doesn't care, and the fight begins. While the battle starts with Cartman beating Wendy, she soon turns the tables and proceeds to give Cartman the beating of his life. She ends the fight just as Mr. Mackey arrives to break it up, shouting "I'm finished!" and then walks away.
Cartman, meanwhile, expresses depression and fear that he's no longer "the cool kid", but when the other boys tell him that he was never cool in the first place, that they all have always hated him, and that their opinion of him "couldn't sink any lower". However, he assumes they're trying to make him feel better. Cartman convinced they would only try to make him feel better if they still thought he is cool, walks away jovial despite his injuries, leaving the rest of the kids dumbfounded by his reasoning.