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1.
the terms refers to the posture one has after receiving anal sex time and time again. those with butt fuck butt are seen with what appears to be an exaggerated slouch when walking or standing, but in actuality it is unreversable muscle damage of the lower back muscles. the term most often refers to homosexual men, but women are also known to sport butt fuck butt.
family member 1: hey is julian, aunt shandra son, gay?

family member 2: hell yeah, look how that nigga walk.....he got that butt-fuck-butt.
by Brent "Witty" March 05, 2010