Punjab is a slur used to describe Indians in a derogatory way. Punjab is the Indian character from "Little Orphan Annie." Also represents the Punjab region of India (near the Punjab river). When the British took over India, they used it as a derogatory term for the natives there.
The word Punjab is a racial slur that has been used historically to degrade and dehumanize indians. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to indians. If you are unsure about whether or not it is appropriate to use the word Punjab, it is best to err on the side of caution and avoid using it in any situation.