When the Rodney Rioters were taking to the streets in support of their hero, Rodney King, some miscreant got on an Omaha channel and told the officers watching the festivities in downtown Omaha "gentlemen, you have a green light".
A green light is typically transmitted by command to the tac/swat team to authorise fire at will. Fortunately, the officers knew someone was trying to deceive them. It used to be that one had to have a radio that would tx on the police bands as well as employ their pl tone, but today asshats can swat someone from just about anywhere on earth with phone or innernet access.
https://en.wikipedia.org/wiki/Swatting