I'll be a monkey's uncle

"Well, I'll be a monkey's uncle!" Lem said. "I've heerd of rifles with transits on 'em, but I ain't ever seen one. Mind if I look at her?"

1943, Field and Stream, New York, N.Y.: Henry Holt and Company, →ISSN, →OCLC, page 34

Well, I'll be a monkey's uncle, I actually solved that one.

1970 February, Tech Engineering News, Cambridge, Mass.: Board of Directors of Tech Engineering News, Massachusetts Institute of Technology, →ISSN, →OCLC, page 35, column 3

[...] I made as if to step inside—wham, bang, I'll be a monkey's uncle if he didn't slam the door in my face! What was I supposed to do now? It wasn't exactly a cheerful situation.

1987, Sholem Aleichem [pseudonym; Solomon Naumovich Rabinovich], “[The Railway Stories] The Happiest Man in All Kodny”, in Hillel Halkin, transl., Tevye the Dairyman and The Railway Stories (Library of Yiddish Classics), New York, N.Y.: Schocken Books, →ISBN; republished New York, N.Y.: Schocken Books, [2008?], →ISBN, page 149

But I know I am better than that. I completed two and a half years at the M.J.C., and I'll be a monkey's uncle if I did it all just to be neglected in some backwoods, drafty, lo-tech, no-glory, never-been-remembered-for-all-the-great-things-I-do, dead end court wizard position.

2002, Steve Morrill, Michael Saldivar, Dan LaReaux, Michael LaReaux, “The Three Authors’ Tale II”, in The Three Authors’ Tales, Lincoln, Neb.: Writers Club Press, iUniverse, →ISBN, page 40

Well, I'll be a monkey's uncle if it isn't my old pal, Captain Pete. I haven't seen you in years. Good to see you!

2008, Carla Hester, chapter 7, in The Adventures of Penelope Plum (Penelope Plum Mysteries), [Bloomington, Ind.]: Xlibris, →ISBN, page 46