anyone familiar with the phrase "his nibs"? is it always pejorative, implying self-importance? m-w suggests it's an alteration of the british "nob" ~ is 'nob' in common use? and is 'nob' a somewhat catachretic (or at least equivocal) metonymic referral to 'head'?

ps: i'd've thought 'hobnob' would be rooted in 'nob' as a superior, but m-w says hob nob means 'have not'. it seems sorta contronymic, that nob would come to mean something opposite of 'have not'.