Coconut Nigger is a slur used to describe Pacific islanders in a derogatory way. They're dark-skinned, hence the "Nigger", and they're from places where there are coconuts.
The word Coconut Nigger is a racial slur that has been used historically to degrade and dehumanize pacific islanders. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to pacific islanders. If you are unsure about whether or not it is appropriate to use the word Coconut Nigger, it is best to err on the side of caution and avoid using it in any situation.