How do you boo a rap legend like Slick Rick "The Ruler"?  That's exactly what happened last night during his halftime performance at Brooklyn's Barclays Center.

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Rick took to the stage during halftime of the Brooklyn Nets/New York Knicks game and performed his classics "Hey Young World" and "Mona Lisa" and then the fans turned on him.  The crowd actually booed the legendary MC through the end of his performance.  Check out the video:

Word has it, the sound was off and he was hearing a delay in his ear plugs.