area 51
Common nickname for a particular maximum-security USAF research facility, situated within a large training range near Las Vegas. While it's known to have been previously used for high-tech aircraft development and Cold War espionage, the facility's current purpose is a closely-guarded secret, which ironically makes it a very famous aspect of various conspiracy theories and general folklore around alien visitors to Earth.
In June 2019, a joke event known as "Storm Area 51, They Can't Stop All Of Us " ostensibly scheduled a raid of the facility for September of that year, notoriously encouraging people to try and dodge bullets by using the Naruto Run. It became such a viral phenomenon that local law enforcement had to explicitly warn people to stay away for their own safety.