Gar is a slur used to describe Blacks in a derogatory way. Redneck term. Short for nig-GAR. Could also refer to the Gar, a fish similar to the piranha, found in streams in the Southern US and eating by many Southern Blacks.
The word Gar is a racial slur that has been used historically to degrade and dehumanize blacks. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to blacks. If you are unsure about whether or not it is appropriate to use the word Gar, it is best to err on the side of caution and avoid using it in any situation.