You've probably given the video one of its 240 gazillion views. The song by South Korean popstar Psy has taken the world by storm. It's also apparently being used as an excuse for gun violence.
The Guardian is reporting that two different gangs were dining at the same restaurant when a dance-off between two members of opposing gangs broke out with one gang member using the Psy dance as a way to provoke the other. That was apparently effective, because a gun battle ensued. Reports say that up to 50 rounds were shot from a 11mm-guns and carbines. Thankfully no one was hurt.