This doesn't have to end poorly. I had a couple of guys wave a shotgun at me a few years back while I was on an extended climb. I couldn't take the idea seriously that they might shoot me and just continued. On the descent, I encountered them again -- as the cops were arresting them. Apparently, someone called them in

I once had an M80 tossed at me and I've had garbage dumped on me too. But those guys were just screwing around. And I've been clipped by idiots but never seriously injured. I've had some things happen that I really didn't like, but I've been lucky enough to never have to deal with a true psycho.