Mispronouncing a word can be embarrassing; in this case, it could be fatal.
Shibboleth means "stream" in Hebrew. In the Book of Judges, following a great battle, Gileadite soldiers challenged suspected retreating Ephraimites to say it - because they knew their Ephraimite enemies could not pronounce sh. As the story goes, 42,000 Ephraimites failed the test and were killed.
Over the years, shibboleth has lost its danger.
Today, it usually describes a trite idea or platitude, or a slogan or catchword.
For example, in an article poking fun at contemporary food trends: "Words like seasonal, local and, best of all, green market were shibboleths for every self-respecting cook from potato peeler on up." (Time, Feb. 2010).