chip on one's shoulder

The saying originated during the 19th century in the United States, where people wanting a physical fight would carry a chip of wood on their shoulder, daring others to knock it off.

• "The city of Herculaneum […] held its neighbors in hearty contempt, like the youth who has suddenly found his man's strength, and parades round with a chip on his shoulder."
• "People are staying home / When they got chips on their shoulder"
• "The young John McCain was a constant breaker of rules, a brawler and a slob, an undersize punk with an oversize chip on his shoulder."
• "[O]ne minute this "Jihadi John" was struggling to get by, and get accepted, in drizzly England, unemployed with a mortgage to pay and a chip on his shoulder, and the next he stands in brilliant Levantine sunlight, where everything is clear and etched, at the vanguard of some Sunni Risorgimento intent on subjecting the world to its murderous brand of Wahhabi Islam."

• chippy
• thorn in someone's side
• chip off the old block
• mote