To me, Season Five is the beginning of the Golden Age. "Towelie" is an episode that is more original than anything they'd done before. Not only do they introduce an all-new character, (a talking towel who likes to get high and warn kids about towel safety) but the episode itself is a classic parody not of any one show but of the whole sci-fi genre.
When Towelie goes missing from a top secret government installation, the boys end up having to rescue him in order to reclaim their Okama Gamesphere. The pace of the episode is incredibly fast, like a real science-fiction thriller. This in spite of the fact that all of the humor revolves around the fact that the boys really don't care what the government is up to! Indeed, Stan's jaded demeanor and his chanting of the words, "don't care, don't care, don't care" become a rallying cry of defiance. From here on in, the boys of SOUTH PARK are in open rebellion against all political correctness and all moralizing from the government, the entertainment world, and the far-out fringes of the Left and Right. The very plotting of the episode reinforces this as the government and Tyna Corp. are revealed to be equally inept, manipulative and deceitful.
While Towelie himself cheerfully admits that he is "the worst character ever" the plotting of the show has never been sharper. The suspense never flags, the boys are always in action, and there's a new sense of teamwork and cooperation between them. Watch them work together to drive a truck ("Break angrily, Kenny!") and you see they've gone beyond the old schoolyard name-calling. Watch Kyle and Stan brainstorm ("Towelie always appeared when we said something about water") and you see the Kirk-Spock chemistry is in full force, while Cartman's down-home "Towel Call" is an unexpected tribute to his redneck roots. Like the Beatles, these four boys started as four strong-willed individuals and they merge before our eyes into one unstoppable force! With all that going on, there's still room for plenty of one-shot humor in this episode, from Mr. Garrison's magnificent statement of gay pride in the showers ("Go on, have your way with me! Fulfill your sick pleasures!") to Kyle's restatement of team loyalty. ("Stan has . . . uh, date-rape psychosis . . . and I've got to be here for him!")
"Towelie" is a Season Five classic, and Season Five itself is the beginning of the Golden Age of South Park.