You are a citizen. If anyone releases anthrax you want to run and hide. You do not want to subscribe to each terrorist on earth. You just want to know if anthrax is released. You register your interest with the event manager. If anyone releases anthrax you will be notified.
The blue and pink citizens will both run and hide when anthrax is released. Only the blue citizen will relax when the red box is clicked. The terrorist is black. The president is red. View source for more info.
blog post about anonymous events