This idiom describes someone who is resentful, bitter, or quick to take offense, often due to a perceived slight, injustice, or sense of inferiority. The ‘chip’ symbolizes a lingering grievance, as if daring others to knock it off and provoke a fight. The phrase is used in social, professional, or personal contexts to highlight a defensive or combative attitude, carrying a critical or cautionary tone. It reflects cultural insights into pride, sensitivity, and the emotional weight of past wrongs, often suggesting that the person’s touchiness stems from unresolved issues or a need to prove themselves.

The phrase originated in 19th-century America, derived from a custom where men placed a woodchip on their shoulder, challenging others to knock it off as a pretext for a brawl. An early reference appears in the 1843 *New York Weekly Tribune*, describing boys ‘with a chip on their shoulder’ seeking fights. The idiom gained traction during the antebellum period, reflecting a culture of honor and confrontation, as seen in Mark Twain’s *Life on the Mississippi* (1883). Its metaphorical use grew in the 20th century, particularly in psychological and workplace contexts, and spread to British English through American media. The phrase’s vivid imagery and emotional depth ensured its widespread use, especially in discussions of attitude and conflict.