Last week’s episode of South Park, titled “You Have 0 Friends” contains a Tron parody.
Here is a brief description of the episode (yes, possible spoilers):
Kyle, Cartman and Kenny make Stan a Facebook profile against his will and he becomes embroiled and frustrated with everyone asking him for friend requests. After he gets fed up with Facebook, Stan tries to delete his profile but is sucked into a virtual Facebook world.
You can watch the whole episode on SouthParkStudios, or a short clip from the Tron segment, embedded below: