Bar Code is a slur used to describe Jews in a derogatory way. Jewish prisoners were tattooed with a number on their arm while in concentration camps. While the bar code was not invented(or at least patended) until after the war, this is a slur in common, although incorrect, usage.
The word Bar Code is a racial slur that has been used historically to degrade and dehumanize jews. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to jews. If you are unsure about whether or not it is appropriate to use the word Bar Code, it is best to err on the side of caution and avoid using it in any situation.