Pizzagate

Claim: Emerged during the 2016 U.S. election, alleging that a Washington D.C. pizzeria (Comet Ping Pong) was the hub of a child-trafficking ring run by Hillary Clinton and other Democratic Party figures, based on supposedly coded language found in hacked campaign emails.

Origins: Spread through 4chan, Reddit, and Twitter in the weeks before and after the 2016 election, interpreting mundane phrases in leaked emails (about actual pizza, among other things) as secret code for illegal activity.

Why it's false: Washington D.C. police investigated and found no evidence whatsoever of any such operation; the restaurant does not even have a basement, which some versions of the theory claimed hid trafficking victims. Every specific claim traced back to unsupported speculation on anonymous forums, with no corroborating physical evidence, victim testimony, or documentation ever surfacing.

Impact: In December 2016, an armed man fired a rifle inside the restaurant believing he was "self-investigating" and rescuing children; no victims were found, and he was later convicted and sentenced to prison. It became a foundational precursor to the later, larger QAnon movement.