Bruce Schneier quoting an account of a British psychological operations campaign in WW2:
On March 30, 1945, “Aspidistra” intruded into the Berlin and Hamburg frequencies warning that the Allies were trying to spread confusion by sending false telephone messages from occupied towns to unoccupied towns. On April 8, 1945, “Aspidistra” intruded into the Hamburg and Leipzig channels to warn of forged banknotes in circulation. On April 9, 1945, there were announcements encouraging people to evacuate to seven bomb-free zones in central and southern Germany. All these announcements were false.
False telephone messages. Forged money. These were fake broadcast about fakes. Absolute genius. Likely still happening today in all sorts of places. Better:
The German radio network tried announcing “The enemy is broadcasting counterfeit instructions on our frequencies. Do not be misled by them. Here is an official announcement of the Reich authority.” The Aspidistra station made similar announcements, to cause confusion and make the official messages ineffective.