My big brother was B.I.G.'s brother
Jay-Z had a close relationship with Notorious B.I.G until his death. Given that Jay succeeded Biggie as the biggest deal in hip-hop, Kanye is setting up this analogy (people who took the SAT before 2005 will remember analogies)
B.I.G.:Jay-Z :: Jay-Z:Kanye
Overall, a very humbling compliment that sums up the same relationship Kanye and Hov have.
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