The phrase "say uncle" means to force some one to say the word "uncle", which means in that circumstance "Enough!" or "I give up." One possible origin of this usage, reported by William and Mary...
His name modelled after Samuel Wilson, a meat purveyor to the United States army during the War of 1812.
le premier oncle
yes ! but not your uncle in text as such....
Saint's Row 2: Street Lessons with Uncle Gary Trailer
Uncle John's Band - Guitar Lesson
How to Make Homemade Pasta Dough a la Uncle Bill
GTA IV Uncle Vlad Mission Guide