It was first used by Dio (in the metal context), and it's some italian sign which is supposed to drive away evil spirits or some shit. You can see it being used on cover on Dio's first album, Holy Diver.
I had to discuss metrosexuals in one of my prelim. English assessment task. The topic was 'Images of Men'....Fucking gay, I tell you....
Anyway, I don't like them, much.