it's a random event that happens sometime in the beginning of any new game — in story, it's a military black hawk helicopter flying over the Knox County area looking for survivors.
The effect in-game is that the zombies in the world all gather around to follow the noise source, which controls and drives a gigantic crowd of zombies around where you're at. It can be very overwhelming, especially when you're just starting out and don't have much by way of structures built.
my friends and I utilize a mod that records your skills in a notebook that stays on your zombie after you die. so you actually have a motivation to go back into somewhere dangerous and clean it up.
still eagerly waiting for the stable release of the next version.
I am a huge fan of his show and watch every night, but I agree, the format is pretty dated. Even the idea of a house band barely makes any sense. I miss 'The Soup' and Joel McHale.
Finally, somebody looking out for the faceless among us.