He's baiting you, waiting for you to call him some sort of "black name". Don't fall for it.
He can claim discrimination on your part.
Even if you are BFFs and it's said in jest. If at a later point there is some tension (he's fired, you get promoted/he doesnt, etc.) he can come back and say, "That person called me Negroid", even tho he used the N-word himself. It's especially helpful (on his part) if a 3rd person overhears you calling him that.
Not only CAN'T you call him Negroid, HE CAN'T use that language either. It works both ways.
CYA fren.
Been there, saw it, lived it.