black man vs tar baby

black man

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

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

tar baby

noun
  • A black person. 

  • A difficult, abstract problem that worsens as one attempts to handle it; a "sticky" situation, especially one where attempts to make it better only make it worse. 

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