Kenny Dies/Butters' Very Own Episode and The Return of Chef.

I sorta think of "fourth grade" and "red sleigh down"/"cancelled" as equally sharp turning points as "kenny dies". going up a grade level has allot of finality to it that kenny dying just doesn't have, mr. garrison coming out of the closet as well in that episode. season 6 definately has a different feel from the earlier seasons, but it also feels different from the later ones. kenny still plays a role in the plot of season six, ironically much more so than when he's alive again in season 7. tweek also falls off a cliff plot wise after season 6.

Chef dying also feels like a big bookend although there wasn't allot of chef in the seasons leading up to it, so it's not as dramatic.

"stunning and brave" for me is for sure the sharpest left turn of the series so far, with the new characters, new format, cartman's new found humility, and all the talk of things changing within the episode.

But you know what, the vaccination special also gives me really strong end of an era vibes. i'd bet we're in the midst of big changes right now, but we shall see.

Vaccination speical

When it comes to seasons: I personally think that season 20 is basically the definitive end of South Park’s Golden Era.

And when it comes to episodes: I personally think that “Scott Tenorman must die” is the end of the classic South Park-era and that this episode and the rest of season 5 and so on, is basically South Park’s transition from being a crazy cartoon to a more serious social commentary cartoon that deals with the ongoing events.

"You're getting old"

Skank Hunt

Definitely the Satan/Saddam two parter from S4 as that was the final time the main kids were in third grade and the last to have the original intro.

Season 22 ep 4: Tegridy Farms