In hip hop (particularly East Coast) slang; a nigga that hides in his shell, so to speak, when the beef cooks - talkin' tough but nowhere to be seen when things get physical.
"Big Noyd, I can't cope, with all these crab niggas trying to shorten my rope" - Mobb Deep
Man 1: “Hey man, who’s that person over there?”
Man 2: “Oh, him? That’s just a NiggerBallSweat Crigger Balldrag Rock Hill NiggaBitch Louisiana Crab Dangler.”