What is 47s?
47s are White people. When Black people are trying to be discreet, and not let the White Man know we are talking about him, we will substitute "47" or "47s" for words/phrases like "white man", "white people", etc.
Black Man #1: Damn white people get on my nerves
Black Man #2: Watch out, Mr. Johnson's right behind you!
Black Man #1: Can't go nowhere without these 47s on your back!