What you did reminds me of this gory movie "kalifornia", about a couple of journalists who, unknowingly, picking up a couple of very sick serial killers on their road trip.
I'm sure none of of those that hitchhike are an actual psycho, but remember the movie next time you stop and pick up some stranger :p
Or: on another real life twist, I remember there was a case in Australia few years ago when a real psycho serial killer drove around New South Wales and Queensland picking up tourists who hitchhiked and then killed all of them in the most sadistic ways.
http://au.news.yahoo.com/thewest/a/-...ders-hysteria/
Hitchhiking is now actually criminal offense in those states.