Cube is a slur used to describe Cubans in a derogatory way. Self-Explanitory
The word Cube is a racial slur that has been used historically to degrade and dehumanize cubans. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to cubans. If you are unsure about whether or not it is appropriate to use the word Cube, it is best to err on the side of caution and avoid using it in any situation.