I almost don't want to write about this at all. I wish I could just let the headline linger. But I can't. It's true. Nirvana is reforming, for one night only, and Sir Paul McCartney himself will be standing in for Kurt Cobain.According to the Guardian, McCartney has been secretly working with Dave Grohl, Krist Novoselic, and Pat Smear (Nirvana's late-period touring guitarist) who haven't performed with each other in 20 years. The quartet is slated to perform tonight at the 12-12-12 Hurricane Sandy benefit concert at NYC's Madison Square Garden, alongside the Rolling Stones, Alicia Keys, Jon Bon Jovi, and a shit-ton of other mega-stars.McCartney is quoted saying: "I didn't really know who they were. They are saying how good it is to be back together. I said: 'Whoa? You guys haven't played together for all that time?' And somebody whispered to me: 'That's Nirvana. You're Kurt.' I couldn't believe it."Frankly, neither can I. Nirvana is my favorite band, but as much as I'm slightly offended by this news, it does make a bit of strange sense. According to Michael Azerrad, Kurt reportedly wrote "About A Girl" after spending an entire afternoon listening to Meet The Beatles! Plus, anyone who thinks that Paul McCartney can't scream need only listen to his grating rasp on "Helter Skelter."No bullshit. This is real. This is really happening. This is the world we live in.Follow Ben on Twitter - @b_shap