Hanlon's razor, eg Max Headroom[1]. Just a couple smart idiots with enough intelligence to override a network signal (a hell of a feat, from what I've gathered) and enough stupidity to use that to moon thousands of people.

The US is full of militias. All you really need is for one to happen to have a cop/ex-cop and a telecom/electrical guy in the same one, and you get this.

[1]: https://en.wikipedia.org/wiki/Max_Headroom_broadcast_signal_...