Paul McCartney and the surviving members of Nirvana didn't do a Beatles song last night at the 12-12-12 Concert for Sandy Relief, which Mick Jagger referred to as "the largest collection of old English musicians ever assembled."

And they didn't do a Nirvana song, either. Instead, they did the smarter thing: A brand new song called "Cut Me Some Slack" recorded "months ago," according to Grohl in a post show interview in which he accurately described it as "heavy as f---."

Check it out below, and click here if you want to see R.E.M.'s Michael Stipe join Coldplay's Chris Martin for "Losing My Religion."

Previously: A 2012 Christmas Music Playlist Follow In the Mix on Twitter