My husband is in property management, and at every building they have codes designating different potential emergencies... You don't want to announce there has been a bomb threat over the radios, because that could cause panic. They also have codes for things that are distasteful, like "Tweety" for a dead bird and "Mickey" for a mouse.

It's not rocket science to break the codes, but it's a deterrent to overreaction. Someone who bothered to figure out the code is likely thinking and not being hysterical.