Former method used by KAOS to contact their agents.
Whenever KAOS wanted to contact their agents in a different city they would hold a parade. The agents would pick up the confetti from the street and the color of the confetti determined their instructions:
Green confetti meant that they were supposed to go ahead with the proposed plan. Red confetti meant, "Stop instantly."
After two years CONTROL was able to discover and destroy the system because KAOS also used white confetti that meant, "Danger, leave the country immediately." The break came when during their last parade it snowed and they all went to Miami.
[Episode #101:"Hurray for Hollywood".]