It's the abreviation for black person beach party. Commonly used instead of black person beach party, because it's a bit of a social faux pas. So instead use BPBP.
See black person beach party.

That party turned into an outrageous BPBP really quick.
I swear to God there was a BPBP on the bus the other week.
by Happy Bear October 6, 2005
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