cry uncle

Example: “His little brother pinned him down until he cried uncle.”

Origin: American in origin, from around 1900, and first documented among schoolchildren using it during playground scuffles — the winning side demanding the other "cry uncle" or "say uncle" as a formal admission of defeat. Why "uncle" specifically is genuinely unresolved. One theory reaches for Irish immigration into 19th-century New England and eastern Canada, proposing the word as an anglicized form of the Irish anacal, meaning mercy or deliverance. A second, offered by etymologists William and Mary Morris, traces it to Roman schoolyard Latin, where children in trouble supposedly cried patrue mi patruissime — "uncle, my best of uncles" — appealing to an uncle's traditional authority as a check on a father's harsher discipline. Neither theory is confirmed, and the word may simply have been an arbitrary choice that stuck.