I unintentionally made something that had a similar effect once.

I wrote an application (back when android phones still had notification leds) that allowed us employees to notify each other whether our boss was in the building or not. A state change could be triggered by anyone from their phone (there was some "debouncing" server side), which then popped up a silent notification on everyone's phone telling them who updated the status, as well as switched the color of the notification LED (green meant the boss had left the office, red meant that he was in).

It got pretty funny watching everyone scramble for their phones as soon as our boss closed the door, each time he had to leave. And of course, they competed to see whose name would show up in the notification.