Uncle! - Idioms by The Free Dictionary
An exclamation of defeat and/or a plea for mercy, especially in an informal physical contest of some kind. Uncle! Uncle! Let me out of this headlock already!
References in classic literature
But bless your hearts and eyebrows, all this sort of thing was nothing to my uncle
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