And they're constantly looking for hidden messages in Sia's tweets to indicate whether or not she's trying to ask for help.
This kid just straight-up tweeted the FBI's Seattle office about it.
And, of course, people are tweeting at Beyoncé as well, demanding she free Sia.
There's even a theory that Sia's elaborate wigs are disguises she uses to hide bruises that she gets from Beyoncé.
How did this whole thing get started? It's sort of unclear. But it possibly could have started with this Billboard article from 2015.
In the article, Sia describes working with Beyoncé as a "writing camp":
Not true of artists like Beyonce, with whom Sia says collaborating is "like a writing camp" and that "she's very Frankenstein when she comes to the songs," taking bits and pieces from various songwriters and asking to hear them mixed together. "In the end, she had maybe 25 songs of mine on hold, and I was very excited to get a couple of them back. Definitely one is on the album."
Which seems to have evolved among Brazilian Sia fans over time into some kind of pop music prison thing? I don't know. It's all very confusing. Interestingly enough, members of a Brazilian messageboard called Pandlr say that they were the ones to actually start the meme seven months ago after reading about Beyoncé's writing camps.