sooskpoosk is a referential term that is not necessarily derogatory, in farsi, referring to black people. much like the term cheshtang
in farsi, which translates literally to "tight eyes" referring to chinese people, sooskpoosk literally translates to "roach skin." the actual traditional pronunciation would be "soosk poost," however it has been abridged within the common vernacular.
while it might seem outrageously racist to call a black person a 'roach skin,' it is important to understand that "soosk" (roach) is a common term for black people in farsi, and is interchangeable with "black."
while that might sound even more racist than before, it is important to realize that the persian language is still in the same state that it was in the 16th century, and the entire concept of political correctness is absurd to iranians.
also, this term is interchangeable with the mildly less offensive "seeyahpoost" which is "black skin."