There are certain things you just. don't. do.

For example, you just don't go to Sweden - home of one of the best bands of all time, ABBA - and proceed to butcher one of their best-loved songs without a second thought.

But that's exactly what Metallica did the other day when playing Stockholm and guitarist Kirk Hammett and bassist Robert Trujillo decided to play an off-the-cuff version of 'Dancing Queen' - and to say that it's one of the worst things you've ever heard is putting it lightly.

Tuneless, tasteless and somewhat embarrassing... stick to the heavy metal, lads.

Watch it below: