First spotted by Ars Techinca, the tag clearly flags any Onion headline which shows up in your News Feed as "[Satire]," though the feature doesn't apply to every parody article just yet.
A Facebook rep confirmed the news to Ars Technica, saying "We received feedback that people wanted a clearer way to distinguish satirical articles from others in these units."
That "feedback" is perhaps best exemplified at the blog Literally Unbelievable, which curates a fascinating and bizarre collection of Facebook users who haven't got the joke. If you're looking for misdirected shock and outrage at its best, treat yourself to a dip in those archives sometime.
Perhaps there's something endearing about the misplaced emotions of people who take The Onion all too seriously, because a lot of the coverage about this change has a slightly downcast feel.
Techradar claims "Facebook is dealing a crippling blow to the art [of satire]" with this change, while Engadget writes, "maybe you should be made fun of if you actually think stories like these are true." VentureBeat simply labels the social media giant, "Dr. Buzzkillington."
But parody is more insidious in the social media age — as evidenced by Gawker blog Antiviral. Some recent examples of parody victims: a prominent science magazine citing research from The Onion, anAP story based off of a joke tweet, and a former White House official duped by a military parody blog.
And thern there's the timeless gaffe made by China's People's Daily, which congratulated North Korean dictator Kim Jong Un in 2012 for being named The Onion's Sexiest Man Alive. Maybe we do need some clearer lines.
The idea of flagging parody sites has been put into practice by at least one other news aggregator —Google News already marks all Onion articles as parodies in its feeds.