From Hell to Breakfast. When I saw the book title in the Alberta Aviation Museum, I did a double take. It was one of those moments when you leap to an understanding of something that you've never consciously thought of before.
The last time I heard the phrase was probably when my father said it, and he died back in 1989. Like D-day, this expression was one of many that originated in WWII, a history that slowly disassociated from the words.
Because of research and writing I've been doing recently, I had a sudden insight about the meaning. Bomber pilots flew their deadly raids at night, losing their brothers in arms and getting their planes shot up. Survivors returned at dawn, then ate a good breakfast before sleeping through the day to prepare for the next night's hellish mission.
Words and phrases enter the language constantly. As time passes, their original meanings are forgotten. New generations still use the expressions, but the stories behind them are lost in the mists of time. I found several definitions of this phrase online, and one origins forum that had the meaning, but no clear or accurate sense of the origin. The site did quote Steinbeck as having used it the phrase in 1939, which could support my idea. By the time the Internet arrived, fifty years had passed and the origin of this expression was mostly forgotten.