User blog:SammRojgar/I can't remember which episode...

Does anyone remember the episode where sam and dean investigate an urban legend out in the woods. something about an axe murderer? but, suddenly the monster changes. It turns out to be a weird symbol on the wall that makes the urban legend come to life based on the collective unconcious of those who see the webpage and image?

for the life of me, i cannot find which episode this was.

please help.