It's like a scene out of a horror movie: an unsuspecting woman pumps gas into her car, only to be summoned inside by a gas attendant who informs her that -- horrors! -- a knife wielding lunatic is lurking in the backseat.

In truth, it is a scene from a horror movie -- the horror movie Urban Legend in fact -- and it far from being a horrifying new trend, this old tale's been with us for decades.