Wiktionary
prep.phr. (context colloquial English) (non-gloss definition: Used to express surprise, contempt, outrage, disgust, boredom, frustration).
Wikipedia
For Christ's Sake is a 2009 comedy film directed by Jackson Douglas written by Jeff Lewis and starring Alex Borstein. This film is about a small town priest named Robert, who finds out his estranged brother greatly needs a cancer treatment loan, but finds out that his brother has used the money to finance a pornographic movie.
Usage examples of "for christ's sake".
I may not be the sharpest arrow in the quiver, but it's laundry, for Christ's sake.
When thou hast come to this, that tribulation is sweet and pleasant to thee for Christ's sake, then reckon that it is well with thee, because thou hast found paradise on earth.
Sleep was the only anodyne, and even then I saw it again, the white flash in the slats of the shutters, heard it again, the dull booming, and Al's voice, startled, what was that, for Christ's sake?
I can't remember how my sister takes her coffee, for Christ's sake.
I have no complicated sense of strategy, for Christ's sake- I probably don't even weigh sixty pounds yet!