Firecracker is a slur used to describe Whites in a derogatory way. White women who date Black men. There used to be a firecracker called a "niggerchaser" but today they are called simply "chasers."
The word Firecracker is a racial slur that has been used historically to degrade and dehumanize whites. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to whites. If you are unsure about whether or not it is appropriate to use the word Firecracker, it is best to err on the side of caution and avoid using it in any situation.