“Let’s run it up the flagpole and see if anyone salutes it” is a catchphrase which became popular in the United States during the late 1950s and early 1960s. It means “to present an idea tentatively and see whether it receives a favorable reaction.” It is now considered a cliché. Sometimes it is used seriously, but more often it is used humorously, with the intention that it be recognized as both hackneyed and outdated. A non-joking equivalent would be “to send up a trial balloon.”
The phrase was associated with the advertising agencies then located on Madison Avenue in New York, and with the “men in the gray flannel suits.” Comedians, when mocking corporate culture, were certain to use it, along with expressions such as “the whole ball of wax” and the use of invented words ending in “-wise” (e.g. “We’ve had a good year, revenue-wise”).
The phrase was also used as an ice breaker between serious moments in the Motion Picture film ’12 Angry Men’ starring Henry Fonda.