See this is what happens when rap's overcrowded with bum
Hopsin is pointing out the fact that their “music” is the cause of the social and personal problems he’s pointed out thus far.
And rap music is way too much about girls shakin' ass in the videos nowadays. “Bum”
“Bum(s) meaning all the rappers out there who promote the lifestyle he disses on in this song, so he’s saying there are too many "bum” rappers and not enough ones like him. Basically calling them ass.
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