The rapper Proof, Eminem’s friend and rap-battle mentor, started the group around 1995; the idea was to create a free-floating group of all-star rappers, the Detroit version of the Wu-Tang Clan. The name stood for both Detroit Twelve and Dirty Dozen. The MCs thought the group would have a Western theme, like a gang of outlaw horsemen–but when they rented The Dirty Dozen, they found it was actually a World War II movie. Effectively doubling the group’s six rappers into a dozen, Proof decided everyone in D12 should have a doppelganger identity. He said, “The whole thing in D12 was to have a personality where you would just say anything. You just didn’t give a fuck. Your persona was almost like a mask to hide behind, know what I’m sayin’?” Eminem was the last one to come up with that mask, but it proved to be worth the wait. In 1997, sitting on the toilet–no, really–he invented the nihilistic Slim Shady identity. “Em took Slim Shady and he ran with it,” Proof said. “He took it way more serious than all of us, that motherfucker.”

(Excerpted from the 2006 book Is Tiny Dancer Really Elton’s Little John?: Music’s Most Enduring Mysteries, Myths, and Rumors Revealed, published by Three Rivers Press, written by Gavin Edwards.)