Mr. Garrison has a sex change at the Trinidad Medical Center. It seems to go fine with Garrison realizing that he has always been a woman trapped in a man's body.
At the Colorado state team basketball tryouts, Kyle fails at making the team and is told by the coach that Jews cannot play basketball, the rest of the boys who did make the team all being tall African-Americans. Stan and Kenny try to comfort the crestfallen Kyle, but Cartman laughs and opts to insult him in order to get a reaction. Kyle instead agrees with the insults, (much to Cartman's displeasure) believing that he cannot in fact play basketball due to his Jewish heritage.
In town, the boys encounter Mr. Garrison (who is now Ms. Garrison), who has just purchased tampons. The boys are confused, but accept their teacher's decision.
At his home, Kyle asks about what a sex change is, to Gerald's disgust as he learns of Garrison's surgery. Sheila does not agree with Gerald, so she explains that people have sex changes and similar transformation surgeries because who they are on the outside does not reflect who they are on the inside. Kyle tells his parents that he completely understands what his mother is saying and realizes that he can relate to Mr. Garrison feeling like a woman trapped in a man's body. He feels like a tall African-American trapped in a small Jewish body because of his love of basketball, rap music, and other things African-Americans enjoy.
Kyle's parents do not want him to have the surgery and became really angry when they discover that Kyle is going to have surgery, and Gerald goes after Dr. Biber, the man who gave Garrison her sex change. Seeing Gerald has a t-shirt with dolphins on, Biber gives Gerald a "dolphinplasty" which turns him into a half-man, half-dolphin being/humanoid. Now convinced surgery is fine, he allows Kyle to have a negroplasty.
Mrs. Garrison and Mr. Slave get in a fight Mr. Slave is upset, saying that Garrison disregarded his feelings and thought only of herself when having the vaginaplasty. Mr. Slave says he hates vaginas, and is outraged when Garrison says he just needs to stop being gay altogether. As Slave leaves, Garrison yells out "Fag!" which ends their relationship.
Garrison now questions why she hasn't had a period and discovers that when a woman misses a period it means she could be pregnant. Garrison believes this is due to all the truckers she slept with and happily goes to Dr. Biber for an abortion. However, she discovers that she can't have a baby or a period, despite being truly a woman. Demanding the process be reversed, she discovers her scrotum has been made into a dorsal fin for Gerald and her testicles have been made into kneecaps for Kyle. Garrison cannot be turned back into a man without these exact body parts, so he takes Biber with her to find them.
Garrison and Biber soon discover that Kyle has gone to try out for the basketball team again, but Biber says he only made Kyle look like a black person, not an actual one. If he ever does anything very athletic such as jumping (which he is bound to do in a game of basketball) his kneecaps could explode. Accompanied by Stan, they go to the basketball match (Kyle has made it on to the team thanks to his surgery). Fighting their way through security, they find Kyle just as he nets the ball. Garrison exclaims, "My balls!" as Kyle hits the ground, with his kneecaps exploding.
Gerald who actually was a dolphin and Kyle who was actually a tall African American were told that they can have their surgery reversed, and Garrison, however, cannot, so she determines she would rather be a woman who cannot have periods than a fag.