There is a very interesting word that is used with extreme frequency in Argentine lunfardo. It is “negro”. As I’m sure you know, this word, literally means “black”. But the very interesting thing is that this word is used between friends all the time, in a more real sense, like we use the word “dude” in English.
There is a super interesting podcast that talks about this: www.bacast.com. Check out Season 1 episode 11.
Very common expressions would be “Que tal negro?”, “Que pasa negrito?” and other variations. This means “Hey man” or “Hey buddy/dude/bro”. And there is certainly nothing negative, in fact it is a term of endearment.
What is incredibly interesting, is the lack of association that this word has with race, even though it is also used, in a very derogatory sense, to mean a person of low class / street person / someone from a poor neighborhood.
In this context, the use would be more like “Che, estos negros siempre estan buscando para robar” or “Jeez, those low-lifes/punks/street kids are always trying to steal.”
Another example would be “Ese es un negro de mierda.” This is extremely insulting but has nothing to do with race. Instead it would mean something like “That guy is a fucking (something… but not the “n” word) dirty thief / criminal / punk (but much stronger).” This can be translated in other ways, but certainly is not indicative of a racial slur.
Yet another example is “Callate negro de mierda” which would be like “Shut up you fucking asshole” (and could be used to insult somebody that cut you off in traffic).
And another example is “Che, todos los Bosteros (Boca fans) son unos negro,” which means that they drink beer out of the can and piss in the street and yell and cause caos.
Negro, then is almost always associated with a person who is a villero, or from villa. A villa in Argentina comes from the full phrase “villa de emergencia” which is a place where someone goes if they have been evicted or are homeless. It is therefore, a word, that when used in a derogatory sense, refers to class, not race. A negro, or villero, is a person of low class, who would be inclined toward violence, thievery, or otherwise untrustworthy and uncivilized behavior.