I turned my boss onto South Park about three months ago. It never occurred to me that anyone with a functioning brain wouldn't have been a dedicated fan since its inception. He's busy catching up with ten years worth of episodes using Shaw's TIVO equivalent device.
My personal favorite episode is the one about Joseph Smith, who founded the Mormon faith. You can't help but watch in astonishment that anything so egregiously bogus (i.e. totally made up by a clearly unbalanced man) could have become, some 180 years later, the fastest growing religion in the world.
The episode where Timmy (in the wheelchair) and Jimmy (on crutches) duke it out pushes the boundaries of political correctness to an area that only South Park would dare to go.