Yak is a slur used to describe Bosnians in a derogatory way. Bosniak shortened to yak, also associated with their smell.
The word Yak is a racial slur that has been used historically to degrade and dehumanize bosnians. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to bosnians. If you are unsure about whether or not it is appropriate to use the word Yak, it is best to err on the side of caution and avoid using it in any situation.