Bounty Bar is a slur used to describe Blacks in a derogatory way. The Bounty Bar is a coconut filled chocolate bar, so it's brown on the outside but white on the inside. An insult to (for example) black police officers in England.
The word Bounty Bar 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 Bounty Bar, it is best to err on the side of caution and avoid using it in any situation.