If you don't get your ducks in a row, you will be replaced.
Baby ducklings swim in
a straight line behind the mother duck. If the ducklings stray to
far, the mother duck will get them back in line, that is get her ducks
in a row.
Alternative: Contrary to popular belief this phrase has nothing to do with little
yellow ducklings following their Mother duck all in a straight line. Landlubbers use the phrase
to mean "get your business organized", but sailors know that this expression comes from
the boatbuilding trade. Unbeknownst to a lot of people, a "duck" is a great big thing,
bigger than your car that is so heavy that it has to be moved with a crane, and has jaws
that open to make it a giant vise. The U.S. Navy (when building a new ship) lines up a number
of ducks with a laser bean so that they are absolutely straight in a line; then the beginning
piece of the new boat (the keel) is clamped in. The ducks hold the keel perfectly straight
so the ship will be absolutely square athwart and fore-an-aft when it is being constructed.
And so the first thing that is done in shipbuilding is to "get your ducks in a row".