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2.
a cool brother.

an informal acceptance of a person into a cult or group
yo, that's my boy. he a coolnig!
by JohnnyWalkerDoesNotWalk December 02, 2012
 
1.
1. An expression commonly used in conversation today in response to another's comments to add emphasis to the word "cool." It is not to be used offensively or in any way degrade the person who to whom this phrase is stated.
Jane: OMG! I had a such a great day today. I went shopping, got my nails done, and met up with Nikki for lunch. I could go on and on about my day, but I don't want to bore you with details!

Nick: Cool nig.
by europekebaad June 04, 2011