Eminem originally performed under M&M, but later this evolved into his full alter ego, Slim Shady. Em explains:

"Slim Shady is just the evil thoughts that come into my head. Things I shouldn't be thinking about. Not to be gimmicky, but people should be able to determine when I'm serious and when I'm not.

"That's why a lot of my songs are funny. I got a warped sense of humour I guess."