Metallica guitarist Kirk Hammett says he made an unlikely friendship when the band toured behind The Black Album -- late Nirvana frontman Kurt Cobain. Hammett tells Rolling Stone that "Whiplash" from Kill 'Em All was Cobain's favorite Metallica song. Hammett adds, "He came to one of our shows in Seattle, on the Black Album tour. I remember at one point, we were playing 'Whiplash,' and he looked at me and kept punching the air with his fist, and gave me a big thumbs-up sign. I was like, 'Cool. Kurt, I know you love this song. This one's for you!' I knew Kurt kind of well, and I hung out with him quite a bit. He was a pretty big Metallica fan -- I was surprised at how much of a Metallica fan he was. He loved Ride the Lightning. He loved that album."