A cop who is totally insane and hell-bent on arresting teens for drinking and breaking up parties, most likely because of a lack of exposure to vagina and real police work. If there was a party nearby, Herder's will often hide in bushes awaiting their prey, then ambush any teen with a backpack or open beer, yelling some nonsense police code or "OH SHIT! ITS THE COPS!".
Guy 1: What happened to you guy's last night?
Guy 2: Fuckin cops busted the party so we were gonna take the trail but i guess Herder was campin out waiting for us so we got a fine and Matt got taken to the tank.