User blog:JackFrost23/WTF?! - A Guy With a Horse and a Gun in a Gang Match Waiting Room?!

I was in a Gang Match waiting room earlier today when one of the players came riding in on a horse firing weapons. Unfortunately his name did not display over his head, but I think I got it from the activity text.

Has anyone ever seen this?

Until today, I just assumed it wasn't possible.

Is it a hack or a glitch?