Uncle!

Uncle!

An exclamation of defeat or a plea for mercy, especially in an informal physical contest of some kind. Uncle! Uncle! Let me out of this headlock already!
Farlex Dictionary of Idioms.

Uncle

verb
See Uncle Sam
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • uncle
  • cried all the way to the bank, he/she
  • the school of life
  • the university of life
  • monkey's uncle, I'll be/am a
  • find common ground
  • common ground
  • silo drippings
  • be on the danger list
  • a tall tale
References in classic literature
'But bless your hearts and eyebrows, all this sort of thing was nothing to my uncle! He was so well seasoned, that it was mere child's play.
The Posthumous Papers Of The Pickwick Club
"What-ho, great uncle! Couldn't lend one a fiver, could one?" Some married, some didn't, and the partners of those that did became, as custom demands, honorary and adoptive aunts and uncles.
Authority's all relative
I shouted out Thats my Uncle! but none of the other boys believed me.
But Richard Burton IS Guys uncle! my mother replied.
The name's Burton... Richard Burton!
During a time of doubt, despair and sickness, a little girl with a performer's smile skipped up to me exuberantly and shrilled, 'Hello Uncle! How are you?' St was like a thunderclap that cleared the skies.
1.2 billion relatives in China: a friendly child gives Tom Duncan the courage to climb China's contemporary Great Wall