Rail-Hopper is a slur used to describe Chinese in a derogatory way. In early America many Chinese were sent to build the railroads.
The word Rail-Hopper is a racial slur that has been used historically to degrade and dehumanize chinese. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to chinese. If you are unsure about whether or not it is appropriate to use the word Rail-Hopper, it is best to err on the side of caution and avoid using it in any situation.