What episode...

I'd go with the Pilot. It the first episode, the best episode (for me), and it's what started it all. They'll end up wanting to watch more. If you show them an episode like for example a mid season 3 episode, then they won't understand who's who, or what is going on cos they won't have seen the first episodes.

bloody mary

You definetly don't want to show them bloody mary first that one was scary you might want to try a funny episode first perhaps mystery spot, tall tales or yellow fever then start with some scary ones thats what I would do!! But every episode is great and its your desicison maybe go with your favorite episode first and go from there!!!

I'd start at the very beginning: 1.01 Pilot. It's the most obvious choice, I know, but it's also the best way to introduce your friends to Supernatural.

Do a combination! First bloody mary(to scare the hell out of them hehehe...) and then... Ghostfacers! :D.

I did this to my friends' first SPN time and they're now hooked! They loved this;

Spruce: "Wow... you're really strong" (or somethin like that)
Dean: -.- *gives him the finger*



Actually the reason why I showed them bloody mary is to teach them a lesson. They borrowed my mirror that I have with me at all times but then they returned it to me broken and said I did it... So yeah that was a lesson for them hehehe :P. But then they wanted more so then I showed Ghostfacers! :)