Bootlip is a slur used to describe Blacks in a derogatory way. During the Industrial boom of the auto industry and OSHA'a requirement of safety precautions, workers were required to wear steel-toed boots. Common steel-toed boots are black in color and have large, bulky toes - referencing the size of black's lips.
The word Bootlip 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 Bootlip, it is best to err on the side of caution and avoid using it in any situation.