When employees at sensitive U.S. government offices work intensely and continuously without breaks, they order from nearby pizza restaurants.
This indicates they are extremely busy with significant political or military events that may be imminent.
The term emerged to describe the correlation between increased pizza orders and the occurrence of important or sensitive events within institutions such as the Pentagon or the White House.
Although this metric is not scientific and is sometimes used for entertainment, it has proven to be highly effective in past instances, with some claiming it has never been wrong.
It is considered by those interested as an open-source intelligence measure for the real world to predict impending significant events.
Examples:
The English Wikipedia page for Pizza Index has been removed for some reasons.
Also Pizza Index information has been monitored decades ago already by Soviet intelligence and was later made public following the collapse of the Soviet Union and the establishment of the Russian Federation.