I'm the deadbeat father of your little brother
In other words goddamnit I'm a bad motherfucker

from J. Cole – Grew Up Fast Lyrics on Rap Genius

If he’s your brother’s dad, that means he fucked your mom! Being a deadbeat (bad) dad would literally make him a bad mother fucker. We see what you did there Cole…

Also, “bad motherfucker” is a term for someone to be respected and possibly feared.

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