Language alt for "Are you sure?", when you can’t provide an undo/"don’t show again"? Success rate of alts?

Are there other, more common ways of phrasing this? I know its better to have undo, but in this case we can't (yet) have undo, or "don't show this again".

Does anyone have experience with results for "are you sure" versus "confirm" or other language, and is there a big difference in success rate/time of response?

This is for cases when it isn't possible to allow an undo, when you are obligated to have the "are you sure" instance.