I have wondered for a long time if the British adjective “chippy”, meaning “appearing ready for an argument or fight”, comes from the metaphor of “having a chip on one’s shoulder”. In Britain “chippy” is an adjective applied to the working classes, generally by their self-styled social superiors trying to imply that the “chippy” attitude springs from resentment at not having the “advantages” (and wealth) that come with a higher social position. The OED has one meaning of “chippy” as “cross, irritable”, but includes it as a figurative usage under “given to chipping, liable to chip”. The New Partridge Dictionary of Slang gives no origin for the expression, and is surely wrong in saying “chippy” means “impudent”: as Britons will know, the comedian Paul Merton, the subject of its example quotation, specialises in slightly surly almost-aggression, which is exactly what “chippy” means to me. Certainly the author Steven Wells in Punk: young, loud & snotty: the stories behind the songs derives “chippy” from “chip on the shoulder”, and references “a man seeking a fight in a pub” daring anybody to knock the chip off his shoulder, before calling punks ready to fight with upper-middle-class students “chippy”.