Not all Facebook users can decipher real news from satirical news. The social network wants to help those confused users from falling victim to joke articles written by websites like The Onion.
If a user clicks on a satirical news story, Facebook then will tag any related links to that story as "satire."
The social media website started the small test run over a month ago after it received feedback that people wanted "a clearer way to distinguish satirical articles from others in these units," a Facebook spokesperson told Ars Technica.
The tag has only appeared on stories from The Onion, but Facebook said its tagging all similar sites like The Onion's sister site Clickhole and The New Yorker's Borowitz Report.
The website Literally Unbelievable documents readers who mistake these stories for truth. Readers have had trouble distinguishing stories like a 9,600-mile roller coaster or Middle East bombings exposing Earth's mantle as unbelievable.
Facebook's new system could have come in handy for people living in Chicago, Illinois and Louisville, Kentucky this past week. Both cities fell victim to "purge" hoaxes based off the popular horror movie "The Purge" and its recent sequel.
Satirical website Cream Bmp Daily posted the fictional Chicago story about teenagers killing 112 people in one night. The post went viral on Twitter and announced other purges in Detroit and Jacksonville, Florida for Aug. 15.
The site does provide a disclaimer on its About page that says its "for entertainment purposes only."
The city of Louisville took the threat for an Aug. 15 attack much more seriously. Police said anyone who posted threatening messages on social media before that night would face criminal charges, according to KSDK.com.
"One lesson is that people really need to be careful about what they say on social media," said Chris Poynter, spokesman for Louisville Mayor Greg Fischer. "We take every threat seriously."
The city did report two shootings, but neither related to "purge" activity.