André 3000. Photo: Taylor Hill/Getty Images Where were you when André Benjamin, a.k.a. André 3000, wore a piano on his back at the Met Gala and carried a trash bag? The multi-hyphenate showed up on the blue carpet in custom Burberry in collaboration with his own menswear line, Benji Bixby , styled by none other than blond Law Roach , confirming his status as one of the most effortlessly cool people living and working right now. But the piano on his back wasn’t just an accessory he happened to