Strap Hangers is a slur used to describe Blacks in a derogatory way. When the whites were sitting on the bus, the blacks had to stand and hold onto the strap.
The word Strap Hangers 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 Strap Hangers, it is best to err on the side of caution and avoid using it in any situation.