"Running up a flagpole" is a common idiom that refers to testing and evaluating an idea or proposal. There are several other phrases and expressions that have similar meanings and can be used interchangeably with this idiom. One such phrase is "floating an idea," which means introducing a concept or suggestion for consideration. Another similar expression is "putting out feelers," which refers to testing the waters to gauge interest or support for an idea or proposal. Finally, the phrase "throwing something out there" can also be used to communicate the act of presenting an idea or suggestion to a group for potential discussion and consideration.