Speaking to BBC 6 Music about the ‘weirdest moment’ of recording the album, Foo Fighters frontman Dave Grohl replied: “The guy from Boyz II Men (Shawn Stockman) walking through the parking lot and me saying ‘would you sing on our record?’ And he does – on the heaviest song on the entire record.”
He continued: “It sounds like Sabbath and Pink Floyd. It’s heavy. It’s the last song on the record. He built a choir – it’s like 40 vocals stacked. It’s insane.”
"Insane" was definitely the word I was thinking of...