"Mystery of the Urinal Deuce" is the ninth episode in the tenth season of the American animated television series South Park.
Later on, Kyle explains that he believes 9/11 conspiracies to be "retarded", though Butters claims the event was caused by George W. Bush: a fact he learned from Cartman.
A SWAT team attacks and takes Kyle, Stan, and the leader of the conspiracy organization to the White House were U.S. officials, including President George W. Bush, reveal that the government really is behind 9/11.
Bush appears to murder the conspiracy leader as Stan and Kyle flee, due to Dick Cheney missing the boys with his crossbow and triggering the fire alarm.
Stan and Kyle intend to travel back to South Park and tell everyone what they've learned, but as they walk along a street in Chicago, they spot the conspiracy leader, discovering that he was not actually killed.
Stan points a gun to Kyle and reveals that he was the one who defecated in the urinal (his reason for doing so was that the stalls were full and he did not want to miss recess).
Back in school, Stan is punished by being made to clean the urinal, while Mr. Mackey lectures him, unintentionally making him laugh.