Some info and a short description of this South Park episode on South Park Zone:
This South Park episode is the 126th and it was first aired on March 9, 2005. It was rated TV-MA in the United States. In the episode, Mr. Garrison undergoes sex reassignment surgery after he decides that, on the inside, he is a woman. The operation inspires Kyle and Gerald, Kyle's father, to undergo cosmetic surgery themselves.
Mr. Garrison gets a sex change operation, but when he realizes he is incapable of having a period, he tracks down the doctor to change him back. Meanwhile, Kyle goes to a plastic surgeon to turn himself black so he can be a star basketball player.
Dr. Biber (the doctor who made the operations) apologizes to Kyle and Gerald, saying he should have told them that the surgeries were cosmetic. He then decided to reverse the surgeries he performed on Kyle and his father for a nominal fee, in which they accept, as they are shown returned to normal in later episodes.
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(The complete plot for this South Park Episode)
Mr. Garrison has a sex change at the Trinidad Medical Center. It seems to go fine with Mr. Garrison realizing 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 can't play basketball, the rest of boys who did make the team all being tall African-Americans. Stan and Kenny try to comfort the crestfallen Kyle, yet Cartman laughs at him. Kyle agrees with the insults to Cartman's shock, with him too believing he can't 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 have surgery, and Gerald goes after Dr. Biber, the man who gave Garrison the operation.
Seeing Gerald has a t-shirt with dolphins on, Biber gives Gerald a "dolphinplasty" which turns him into a half-man, half-dolphin. Now convinced surgery is fine, he allows Kyle to have a negroplasty.
Mrs. Garrison breaks up with Mr. Slave who is angry, saying that Garrison disregarded his boyfriend's feelings and thought only of himself when he had the operation.
As he has now been persuaded to endorse cosmetic surgery, Gerald Broflovski allows his son to undergo the negroplasty. Meanwhile, Mrs. Garrison is puzzled by the absence of his period. After a very confusing period and dialogs, Mrs. Garrison want to change back, but Dr. Biber explained that the operation is irreversible, as his parts was used in Kyle's knees to make him taller, and into Mr. Broflovski's dorsal fin.
At the all-state basketball game, Mrs. Garrison, Dr. Biber, Mr. Broflovski, and the other three boys are trying to stop Kyle from playing basketball, as any jumping could cause his knees to explode. Unfortunately, in a dramatic climax, Kyle leaps into the air, causing his new "kneecaps" to explode as he lands. After this scene, Garrison accept his/her "new gender".
Dr. Biber then apologizes to Kyle and Gerald, saying he should have told them that the surgeries were cosmetic; he then decided to reverse the surgeries he performed on Kyle and his father for a nominal fee, in which they accept, as they are shown returned to normal in later episodes.