I speak entirely from memory here, so I may well be mistaken. [/disclaimer]

I have a feeling that "his nibs" was used, in C18/C19 England, at least, to mean "the Devil" (a name that should not be spoken lightly, of course, in case you summon him from the deeps. Therefore the large numbers of pseudonims under which that dark gentleman shelters.) So, if you refered to any one in a pposition of authority over you as "his nibs," you were being rather more than disrepectful.

So far as cribbage is concerned (and I think TED might support me over this) the term for a the point gained for having a Knave (or Jack) of the same suit as the turn-up is either "One for his Nob" or "One for his head", whereas the term for turning the Knave up is "Two for his heels."
Certainly, these are the terms used in England, over most, if not all, of the country.