The INSIDER Summary:

• There's a conspiracy theory online that Avril Lavigne died and was replaced by someone else.
• A long thread about the theory on Twitter inspired a new meme: "a conspiracy thread."
• With the meme, people wildly allege that something has been replaced without anyone noticing.

On Friday,a conspiracy theory about Avril Lavigne shook the celebrity gossip world, and the aftershocks are spreading through the meme universe.

"avril lavigne is dead & was replaced by a look alike [sic],"Twitter user a divinite feminine asserted.

She followed it up with a colon, and then a phrase now becoming famous around the web: "a conspiracy thread."

In more than 50 tweets, the Twitter user argues that Avril Lavigne was replaced by a woman named Melissa Vandella, who Lavigne allegedly hired as a doppelganger to confuse the paparazzi. The real Avril, she says, is dead.

The conspiracy theory that Lavigne is deadhas circulated around the internet for awhile, but this Tweetstorm updates the theory by naming Lavigne's alleged replacement and by positing that Vandella replacing Lavigne explains why the musician's sound changed so much between her2004 moody pop-punk album "Under My Skin" and2007's bubblegummy "The Best Damn Thing."

The whole thing is nonsense, of course. Like many conspiracy theories, it's filled with falsehoods and needless complexity.

But it's fun, and the wild accusation spawned a new meme on Twitter where people allege something in their life has been replaced without anyone noticing.

A lot of the memes are used to joke about long-running television shows, where actors for the same characters are replaced and designs are updated.

Or for other switcheroos in pop culture:

But the best versions of the meme, as usual, are the self-deprecating ones:

The 'conspiracy thread' meme has forerunners.

The meme's appeal — wild accusations and a sense of loss — have existed in other memes that precede it.

"A conspiracy thread" is a similar version of"It's time for some game theory," which originated ina long, far-out Tweetstorm frompolitical analyst Eric Garland theorizing about Donald Trump's ties to Russia. It captivated parts of the political establishment —and was then widely mocked as a meme.

Like the "game theory" meme, people who engage with the "a conspiracy theory" meme have fun making wild-yet-trivial speculations while ignoring a need for evidence.

The "conspiracy thread" meme also recalls "Shazaam," an ostensible movie where the comedian Sinbad stars as a genie.It never existed, but hundreds of people think it does, possibly because of the Mandela Effect.

Both memes have the same emotional appeal: people can mourn a pop culture artifact now lost to them. With "Shazaam," the beloved movie from childhood can never be watched again, because it never existed in the first place. There's a sense of absence that can't be fulfilled.

It's the same with "a conspiracy thread." The old Avril Lavigne, who madesongs like "Complicated" and"Sk8er Boi" is gone. Now we have an Avril Lavigne who makessongs like "Hello Kitty" and"Let Me Go." It would be nice if we can get the old, punky Avril back instead of the glossy pop Avril we have now. But she's not dead, and she's the only Avril we have.

Representatives for Avril Lavigne did not respond to INSIDER's multiple requests for comment.