A situation in which one can't win. For example, If I invite Aunt Jane, Mother will be angry, and if I don't, I lose Jane's friendship—I'm damned if I do and damned if I don't. Eric Partridge suggested this idiom may have come from the emphatic
I'm damned if I do, meaning “I definitely will not do something,” but despite the similar wording the quite different meaning argues against this theory.
[ ; first half of 1900s