So Slim Shady is a name that rapper Eminem gave to himself for some of his songs. Think of it like a nickname. When he's rapping as Slim Shady, he's usually saying really crazy and silly things that he wouldn't normally say as himself. It's like he's pretending to be a totally different person. It's kind of like when you pretend to be a superhero or a princess when you play with your friends. Does that make sense, little friend?