Niggas wearing flags cause the colors match they clothes
They get caught in the wrong hood and filled up with holes, motherfucker

from 50 Cent (Ft. Eminem) – Patiently Waiting Lyrics on Rap Genius

Meaning

“Wearing a flag” is hanging a bandanna out of your pants pockets in order to represent gang affiliation. Blue is for Crips and red is for Bloods. 50 is calling these guys posers: they base their choice of bandannas on whether it goes with their outfits, not whether it represents their gang

This is a two-layered diss: not only are they pretending to be gangsters when they’re not, but their concern with color coordination is both vain and not exactly tough

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