A baseless conspiracy theory that Joe Biden would wear an electronic device in his ear during the first presidential debate on Tuesday went viral on social media hours before the event.

Why it matters: The conspiracy originated on social media before appearing in a text message sent by President Trump’s re-election campaign to supporters. It was then regurgitated by media outlets like Fox News and New York Post, who cited the Trump campaign, throughout the day, according to NBC News.

• Kate Bedingfield, communications director for the Biden campaign, called the rumor “completely absurd” during a call with reporters on Tuesday.

How it worked: Baseless memes calling for a third party to inspect Biden's ears before the debate saturated Facebook Tuesday morning.

• One particular meme was simultaneously posted by multiple Facebook pages with names like “US Conservative” and “The Unhinged Left” and received thousands of shares, according to NBC.
• Fox News, New York Post and Breitbart then published stories claiming that the Trump campaign wants the Biden campaign to allow a third party to inspect the ears of each debater for ear pieces and that Biden had not yet agreed, citing the Trump campaign.
• The stories received tens of thousands of shares on Facebook and Twitter, despite being based on nothing more than anonymous accusations on social media and from the Trump campaign. White House press secretary Kayleigh McEnany shared the rumor on Twitter, receiving tens of thousands of interactions on her own page.

Our thought bubble, via Axios' Ina Fried:It's just the latest example of how false information can easily gain traction on social media, spread unchecked, and eventually become a subject of discussion in both partisan and mainstream media.

The big picture: The earpiece conspiracy was not the only example of viral misinformation spreading ahead of the the debate. On Tuesday morning, "Fox and Friends" allowed Rudy Giuliani, Trump's personal lawyer, to repeat a baseless accusation that Biden is taking "performance enhancing drugs" to help his debate performance.

• Trump has repeated the accusation multiple times over the last month without offering proof. The president even suggested that both men be drug tested before the debate, an offer Biden’s campaign rejected.

Go deeper: Election influence operations target journalists