I've never been able to find the meaning of guinea in regards to Italians and I've asked a lot of them. Anybody got any ideas?
Here's what I found using Google...
Guinea
region along the west coast of Africa, presumably from an African word (perhaps Tuareg aginaw "black people"). As a derogatory term for "an Italian" (1896) it is from Guinea Negro (1740s) "black person, person of mixed ancestry;" applied to Italians probably because of their dark complexions relative to northern Europeans, and after 1911 it was occasionally applied to Hispanics and Pacific Islanders as well.
Never heard that, maybe. I haven't heard it applied to anyone but Italians though. But why Guinea and not some other random African nation?