A silly joke about a parrot made the rounds of 19th-century American newspapers and may be the source for our expression “cry uncle,” meaning “to give up.” The anecdote features a boastful owner who orders a pet parrot to speak the word “uncle” but the bird refuses. The angry owner locks the animal inside a chicken coop and when the owner returns later, he discovers a massacre—the parrot killed all the hens except one. The parrot stands over the sole survivor and yells the exact same command at the hen to force a surrender: “Say uncle!”This is part of a complete episode.
This explanation, of all you have ever given, seems the most contrived. Why was being used as the word for the parrot? This seems more like a joke based on an existing expression — which brings me to the theory I accept…
In “How The Irish Invented Slang,” by Daniel Cassidy, he claims that the Gaelic word for mercy is “anacal” (loosely pronounced ahna-kaal). The influx of Irish immigrants is what brought this saying to America, as well as a book of other expressions. Most of these expressions were not written in literature, so it’s easy for their origins to be lost
Just to get it on the record here, Daniel Cassidy’s book is terrible and not to be trusted, and his supposed etymology of “cry uncle” is a bad one. Here’s my takedown of his awful book: https://grantbarrett.com/humdinger-of-a-bad-irish-scholar/