Xarnego is a slur used to describe Spanish in a derogatory way. Originally meaning people whose ancestors came from different parts of Catalonia, and later Spanish-speaking people that migrated into Catalonia.
The word Xarnego is a racial slur that has been used historically to degrade and dehumanize spanish. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to spanish. If you are unsure about whether or not it is appropriate to use the word Xarnego, it is best to err on the side of caution and avoid using it in any situation.