The state of being that results after an individual has become SUCH a heavy metal fan, that they lose their sense of reality. Their entire life becomes a "Metalfest" of just sitting in their apartment or parent's basement and headbanging
to any form of heavy metal all day long.
"Hey, have you seen jake?"
"Nah, I think he was up all night watching Headbanger's Ball and listening to Rammstein."
"Damn man, that guy is just metally retarded."