Anyone who's ever played the card game cribbage will be familiar with the call one for his nob, which is made when a jack (knave) gains a point. In fact, being able to call one for his nob is probably the best thing about the whole game of cribbage.
So, does that mean a nob's a knave?
Well, not necessarily. In Britain a nob is someone whose importance is largely due to his family connections. A nob might be a lord, perhaps; someone who arrives with ready-made importance but not a ready-made suit.
If those sorts of nobs are rare in your part of the woods then nob also means head, as in the old rhyme about Jack, who, together with Jill, went up the hill to get a pail of water (though why some idiot decided to dig a well on the top of a hill I cannot imagine) and, after tumbling down, had his nob patched by old Dame Dob with vinegar and brown paper.
As you will have noticed, these sorts of nobs are absolutely everywhere.
It's absolutely essential to bear in mind that you see one whenever you look in a mirror.
Spot the Frippet: nob. The words for the card and the important person arrived in English in the 1800s, no one knows from where. The word for head might be a variant of knob, which comes from the Middle Low German knobbe, knot in a piece of wood.