Ben Pruchnie, Getty Images / Twitter: Krist Novoselic Throughout the 12-12-12 Concert for Sandy Relief at New York City’s Madison Square Garden, a monumental bulk of talent occupied the grand stage. During the charitable event, which lasted for over five hours, legendary artists such as Bruce Springsteen, the Who and the Rolling Stones performed for a worldwide audience, but the true highlight of the night was the collaboration between Beatles legend  Paul McCartney  and  Nirvana members Dave Grohl , Krist Novoselic and Pat Smear (touring member) on the new song ’Cut Me Some Slack.’ Earlier in the day, there were rumors that McCartney would be singing the late Kurt Cobain’s parts for some Nirvana covers, but the collective instead performed an original track that they had written during an impromptu jam session . Bassist Krist Novoselic tweeted earlier that the song was “kind of ‘Helter Skelter’ meets ‘Scentless Apprentice.’ It rocks with a heavy groove. St. Paul is powerful.” Novoselic also tweeted out the above photo of himself with Grohl and Smear. ‘Helter Skelter’ ended up being the first song Sir Paul played as he finally to, followed by ‘Let Me Roll It,’ ‘Nineteen Hundred and Eighty-Five’ and ‘Blackbird’ among others before the one-time Nirvana musicians joined the Beatles legend. Throughout the 12-12-12 show, the official Foo Fighters Twitter page had been posting pictures of single letters in succession, eventually spelling out, “Cut Me Some Slack.” Rocking an electric ukelele and a glass guitar slide, McCartney showcased his trademark howl in the new track ‘Cut Me Some Slack,’ which mixed a heavy Nirvana sound with a ‘Helter Skelter’ attitude. The band was so incredibly tight, you would have sworn that the group were playing together for years. Grohl, in particular, was a beast on the drums. (Watch a clip of the performance below.) The song was genuinely mind-blowing, and the good news is that it will be the first cut on the soundtrack to Dave Grohl’s ‘Sound City’ documentary, according to a Foo Fighters tweet after the performance. Before McCartney’s performance with the members of Nirvana, the audience was gifted with the voice of Pearl Jam ‘s Eddie Vedder earlier in the night. The singer took a spot next to Pink Floyd legend Roger Waters to sing the rock anthem ‘Comfortably Numb.’ Vedder’s voice fit perfectly within the Pink Floyd standard, offering a diverse cadence to the track while switching back and forth with Waters. For more on the 12-12-12 Concert, click here . To donate to the relief efforts, click here . Watch a 30-Second Clip of McCartney + Nirvana Members Performing [button href=”http://loudwire.com/20-things-you-didnt-know-about-nirvana-nevermind/” title=”Next: 20 Things You Didn’t Know About Nirvana’s ‘Nevermind'” align=”center”]