It was a derogatory way to call south American fur sellers who traveled to Europe during the nineteenth and early twentieth centuries. It was the French who began to call them rastaquouère (something like "drageers") who actually applied more for their attitude of "nouveau riche", who boast of their money. And so he came to America, where he is also used as a "liver, who takes advantage of the generosity of others." See Rastacuerism.
