Well known, errr, polarising Canadian rock band Nickelback - brains behind such softcore alt-rock classics as 'How You Remind Me' and the abundantly-memed 'Photograph' - are known to have covered songs from iconic metal bands during their live shows. Search ‘Nickelback covers’ on YouTube and you’ll see they’ve covered a ton of bands, including Pantera (link) and AC/DC (link), in the past. Just recently however, a (since deleted) Facebook video of them covering Sad But True by Metallica went viral and Metallica fans became the confused kind of mad, but mainly because they actually do a pretty great take of the song: