Meaning something is very straight and silky, can be used for anything. Taken from the popular 'Fellowship of the Lube' video.
"But I don't really give a fuck, cause my beard is still permin like a mah'fucka."
Used when describing something that is 'perfect' or 'really impressive'.
Tim: Bro, this lasagna is permin
Harry: Most permin meal I've ever had in a while cuz