After a Mercedes car driver passes one truck on the right shoulder and then brake checks the truck in the left lane, the dash cammer lays on the airhorn to let the car driver know how he feels.
From the video description: “A truck driver is legally overtaking another truck. This ticked off a driver in a Mercedes. He illegally overtakes the two trucks over the emergency lane before he performs a brake check.”
Here are some other videos of truckers who wielded their airhorns as a form of punishment: