black man vs nig-nog

black man

noun
  • A male adult member of an ethnic group having dark pigmentation of the skin, typically of sub-Saharan African descent; or the appearance thereof. 

  • Used other than figuratively or idiomatically: see black, man. 

nig-nog

noun
  • A person of color, especially, a black person. 

  • A foolish person; hence, a raw and unskilled recruit. 

How often have the words black man and nig-nog occurred in a corpus of books? (source: Google Ngram Viewer )