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
by taste_u September 22, 2006
A crab nigga is a person that tries to pull you down while your climbing to the top ! (Sort of like real crabs in a bucket)
Defined..Crab nigga trying to pull me back ... Crab nigga trying to stop my shine !
by Drock973 June 07, 2016