Hob nob

I pray you sir, what is he?
Sir Toby:
He is knight, dubb'd with unhatch'd rapier, and on carpet
consideration, but he is a devil in private brawl. Souls and bodies
hath he divorc'd three, and his incensement at this moment is so
implacable, that satisfaction can be none but by pangs of death
and sepulchre. Hob, nob, is his word; give't or take't.

The phrase "hab nab"—or "hab or nab"—had been around for about seventy years when Shakespeare's Sir Toby Belch put an irreversible spin on it and gave us "hob nob." "Hab" probably originated as a verbal form, perhaps as a particular mood of "have"; "hab nab" would then be akin to other verbal phrases such as "willy nilly" ("will I, nill I"). In older English, some verbs could be negated by changing the first letter to "n"; the "nill" of "nill I," for example, means "will not." If this model applies to "hab nab," then "nab" means "hab not" or "have not." As we can see from Sir Toby's phrasing, he equates "hob, nob" with "give't or take't," that is, give the knight the stab or take it from him. The phrase went through some interesting twists after Shakespeare; "hob, nob" became a drinker's phrase, referring to the trading off of draughts. Almost immediately the phrase was turned into a verb, was eventually cleaned up a little, and came to mean "fraternize" or "hold familiar conversation." In a continuing process of gentrification, the phrase arrived at its present-day meaning.