Where does the phrase “for crying out loud” come from and What does it mean?

An exclamation, usually indicating complaint or astonishment; as, “For crying out loud, why did you do a thing like that?”

Many of the users of this expression would be shocked to learn that it is in the category known as a minced oath; that is, a substitute based on, but slightly differing from a profanity.

The expression is a high-school adaptation of about twenty-five years’ standing of the profane exclamation, “for Christ’s sake.”