system
Given the following post, respond as if you're commenting on Reddit:
human
[South Park] Why can the characters sometimes remember Kenny dying, while other times they can't?

Throughout the series all the main characters get used to Kenny being unable to die. He keeps coming back, born anew with all his memories including the horrible pain he's been through. When that fails he can just fucking appear out of thin air. Oh, hi Kenny.

There's plenty of examples of everyone in town knowing about Kenny. "It's ok, Kenny dies all the time." "Haha, nice one!" By the gnome episode Kyle and Stan just go through their routine quickly and resume the conversation.

It's not limited to the main kids. The whole town is well aware. In one episode Timmy gives Jimmy an orange parka as a gift, and sure enough, the higher powers in this world do everything they can to try and kill Jimmy when he wears it.

But whenever Kenny's death is dramatic, or meaningful, or lasts longer before he returns, it's like people forget. There's video and photo evidence, like when the roller coaster killed him. There's government agencies in this world specifically for investigation into all the paranormal bullshit that goes on. 

And yet everyone is shocked and in disbelief when they learn the truth about Mysterion. Not one person in South Park seems to remember anymore. Kyle and Stan don't offer consolation and say gee, I never thought about it that way, it must really suck for you. Cartman doesn't make fun of him for dying again and again.

What force or entity is screwing with everyone's memory? Is it unique to South Park, or a worldwide effect? Does it have anything to do with whatever power makes people forget all the other weird things that happen in their world? Like how talking animals and inanimate objects are normal, yet Token is shocked by talking lions.

We know that God is real, and Satan, Jesus, Moses, Santa, and other powerful beings. Is death itself, or the Grim Reaper, real and on a pissed-off vendetta against Kenny? When Kenny killed Death in a dream, was that less metaphor and more literal description?
gpt
Kenny's curse comes from an Elder God, similar to Cthulhu. The rebirth, the memory loss, the lack of terror, everything.

But South Park is a town of powerful beings. Jesus, Satan, sentient towels and feces. Sometimes the power clashes against the curse, weakening the memory loss.