In 1991, I was celebrating New Year's in Brno, Moravia. My girlfiend told me not to go outside at midnight.

When midnight hit (or maybe a few minutes before), gunfire erupted throughout the city. People were taking to their balconies and back yards to fire rifles in pistols. When bullets go up, they eventually come down.

For a communist country that was not supposed to have much gun ownership, there were a lot of guns in those few minutes. I think this was the people's way of telling the government do not piss the people off too much.

In the USA, the intent is probably similar: "We are ready to do some really crazy stuff. Be careful."