The boys have a new fellow student in their class, the mentally and physically handicapped Timmy, who is only capable of saying his own name, the phrase "libalah", and otherwise a very limited number of words.
They send him to a doctor who diagnoses him in a very odd fashion (reading The Great Gatsby in its entirety, then asking one random question about a mundane detail from the book).
Without the burden of homework, Timmy finds a new pastime as he is discovered by The Lords of the Underworld (the rock band consisting of Shelley Marsh's ex-boyfriend, Skyler, and his two friends, as seen in the season three "Cat Orgy"), which takes him on as its new lead singer.
Cartman develops a side effect from Ritalin that causes him to see pink Christina Aguilera monsters (one of which causes him to accidentally kill Kenny).
As the pharmacist and doctor who prescribed the Ritalin are counting their profits, Chef angrily tells them that they are responsible for the children liking Collins.
Horrified that they are responsible for this, they make a plan to distribute an antidote called "Ritalout" (which, in one scene, is in a bottle labeled MDMA) by mixing it into free drinks at the Lalapalalapaza festival.
The plan works perfectly; all the symptoms of Ritalin wears off, Collins is booed from the stage, and the crowd starts chanting for Timmy.
"[1] Collins' appearance and mannerisms in the episode are similar to the "Gumby" character as seen in Monty Python's Flying Circus, one of Stone and Parker's influences.
[3] As explained in the FAQ section on the official website, "When the year 2000 was coming up, everyone and their brother had '2000' in the titles of their products and TV shows.