In a room full of headliners, from Bruce Springsteen and Billy Joel to Roger Waters and Alicia Keys, Paul McCartney and Nirvana stood apart from the rest at the 12-12-12 Sandy relief benefit concert on Wednesday.

Word spread ahead of the event that McCartney was going to join members of the influential rock group for a reunion set, but it was still a thrilling surprise to see McCartney take the stage with Dave Grohl, Krist Novoselic and Pat Smear.

The trio joined McCartney after the legendary Beatle gave a little story about how the reunion came together.

"So recently, some guys asked me to go and jam with them," McCartney told the crowd Wednesday. "So I showed up like you do, ready to jam. And in the middle of it these guys kept saying, we haven't played together for years. The penny finally dropped, I finally understood that I was in the middle of a Nirvana reunion."

And with that, they swung into a well-received performance of a song called "Cut Me Some Slack."

But that was just the highlight of a night filled with them, including Chris Martin and Michael Stipe's duet of "Losing My Religion," Jon Bon Jovi joining Springsteen for "Born To Run," and Kanye West's 20-minute performance, representing as the sole hip-hop act in the lineup.