barn kid

Any person, typically of rural decent, who misbehaves according to social norms. E.g. shouting, fighting, or loudly arguing in public, especially to the point of making nearby spectators uncomfortable. In other words, anyone who shamelessly behaves as if they were raised in a barn.

This was an amazingly beautiful wedding reception, until those god damned barn kids showed up and started throwing Klondike bars at oncoming traffic.