run it up the flagpole

Example: “It's just a rough idea, but let's run it up the flagpole at Monday's meeting.”

Origin: Advertising jargon from 1950s Madison Avenue, and the original was a full sentence used as a stock joke: run it up the flagpole and see who salutes it. It circulated as a specimen of agency-speak — the kind of line writers put in the mouths of ad executives to mark them as fluent in a language of confident nonsense — and it appears in that satirical role in American film and fiction of the mid-1950s. The image underneath is sound enough to have outlived the mockery: raising a flag commits you to nothing, costs almost nothing, and yet tells you immediately whether anyone is prepared to stand behind it, which is exactly what floating a proposal informally is meant to establish.