This means to be on the closest possible terms of friendship. The phrase comes from ‘hob’ and ‘nob’ which meant ‘give and take’, which was a corruption of the earlier Anglo-Saxon hab and nab, ‘to have or not to have’. As good friends tend to stand by and help each other out, particularly when one of their number has fallen on less fortunate times, the interpretation of the phrase becomes clear. To ‘hobnob’ also applied to intimate friends drinking together and Charles Dickens conveys something of this relationship and convivial atmosphere in Great Expectations …
“Have another glass!”
“With your hob and nob” returned the sergeant.
Words by Adam Jacot de Boinod, author of The Meaning of Tingo and Other Extraordinary Words from around the World, published by Penguin Books and creator of the iPhone App Tingo, a quiz on Interesting Words