"black metal ist krieg" (translates to "black metal is war") is the titletrack of an album by german black metal act nargaroth (soloproject of rene wagner aka "kanwulf" or "ash"),
released in 2001 through no colours records, a black metal label with a rather large percentage of NSBM (national socialist black metal) in it's repertoire.
it is notorious for it's simple lyrics ("black metal ist krieg", "black fucking metal ist krieg", "ihr wichser es ist krieg", "fuck, metal ist krieg"),
structure (the song only has 2 riffs, the first is plaed for the first 3 minutes straight, the second one for 2 minutes),
a stolen riff (stolen fron norwegian black metal band strid's song "end of life")
and wagner's photograph on the cover, closely resembling one of varg vikernes .
everyone who takes even remote interest in (black) metal knows this song or at least the title,
it became a well known phrase in- and outside of the black metal scene.
it is being used both seriously or jokingly and spawned several parodies.
so, i wonder if it's widespread enough to be seen as a meme, since it is mostly limited to the extreme/ black metal community, but it's definetly been around for a long time now and like i said it's spread is not entirely limited to metal listeners.
(dammit i wrote nargaroth wrong in the title, too many ~oroths and ~aroths in black metal :P )