First the Fat Boys break up,
The Fat Boys was a hip-hop group from the early 80’s that broke up in the early 90s. The group was very influential on rap in the 80s and, given that they were from Brooklyn, the Fat Boys probably meant a lot to Jay-Z
Aslo, in the movie ‘Boomerang" Chris Rock says “First the Fat Boys break up, and now this”. This is what Jay is alluding to in this line.
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