The phrase is difficult to understand as it stands. 'Rough black' gives some physical characteristics, but 'd l' and 'dp' are not standard English words or abbreviations that I know of. It might be a creative or code - like expression from a specific sub - culture or just a random string of words that don't really have a common meaning.
I can't really make much sense of it directly. It could be a misspelling or some sort of very specialized terminology that I'm not familiar with.
It's a really strange phrase. If we break it down, 'rough' might imply a certain quality, 'black' is a simple color description. But the 'd l' and 'dp' are mysterious. It could potentially be part of an in - joke, or perhaps it was typed out wrong. Without more information, it's almost impossible to fully understand what this 'story' might be about.