Big Sean had a concert Friday night in Detroit, and the crowd went insane when Eminem came out and gave a rare, surprise performance.
The crazy thing ... Em wasn't the only thing in Sean's bag of tricks. He also brought out Lil Wayne, Jhene Aiko, Mike Posner, Dej Loaf, Danny Brown, Trick Trick, Royce da 5'9.
Check out the video ... it's Beatles insane.
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