Metallica and Miley Cyrus performing together? Possible as long as its on April 1 of every year.

In an excerpt:

Dolly Doppelganger) Metallica, in an attempt to capture the financial power of the lucrative tween market announced today that they will co-headline a summer tour with Miley Cyrus. And Cyrus is to join the band as a back up vocalist and harpsichordist.
The co-headlining tour will be called “The Best of Both Worlds” and will feature full sets from both Cyrus and Metallica. To commemorate the historic partnership, Metallica’s upcoming album is to feature a bonus track that features Cyrus on the touching father/ daughter power ballad version of ‘achey, breaky heart’ that the band recorded last month at a bay area mall, to test fan reaction.

When Hannah fans heard news of this announcement, concert tickets immediately sold out, despite not being on sale yet.

source here.