It's pretty tough to know how to react when someone does something like this. I see behavior similar to this most nights on my way home from work, but never anything so extreme. Just drunk people trying to steal traffic signs or other feats of drunken or drug-induced strength. I mean, if I saw something like this I'd call the cops but I'd be scared shitless because the man just put his head through a window and get away from the scene before I did so.
That being said, judging by the one man's gesticulations, I think Binro's right: "Pete's drunk and uhhhh oh shit let's go boys." This is why I go to bars alone.