When you've been around someone long enough that you have a lot of shared context (Mrs. O and I are celebrating our 30th anniversary in February, and we were together a years before that) you develop this shorthand language that only means something to the two of you. (Also useful to identify clones or other duplicates.) If you're both fannish, a lot of your metaphors are genre-derived. One of our favorites is "And they never saw him again" from Stephen King's THE STAND. If you've read it you can guess when this might be used.
Any others that y'all want to reveal?