BDN is a slur used to describe Blacks in a derogatory way. "Big Dummy Nigger" Comes from the movie "The Green Mile". A white prisoner calls a black prisoner a Big Dummy Nigger.
The word BDN 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 BDN, it is best to err on the side of caution and avoid using it in any situation.