A Shibboleth is any custom or tradition, usually a choice of phrasing or even a single word, that distinguishes one group of people from another. Shibboleths have been used throughout history in many societies as passwords, simple ways of self-identification, signaling loyalty and affinity, maintaining traditional segregation, or protecting from real or perceived threats.
The term originates from the Hebrew word shibbólet (שִׁבֹּלֶת), which literally means the part of a plant containing grain, such as the head of a stalk of wheat or rye; or less commonly “flood, torrent or ford” (possibly a head of grain by a water ford).
The modern use derives from an account in the Hebrew Bible, in which pronunciation of this word was used to distinguish Ephraimites, whose dialect used a differently sounding first consonant. The difference concerns the Hebrew letter shin, which is now pronounced as “S” (as in shoe).
“Then said they unto him, Say now Shibboleth: and he said Sibboleth: for he could not frame to pronounce it right. Then they took him, and slew him at the passages of Jordan: and there fell at that time of the Ephraimites forty and two thousand.” -Judges 12:6 KJV
A “furtive shibboleth” is a type of a shibboleth that identifies individuals as being part of a group, not based on their ability to pronounce one or more words, but on their ability to recognize a seemingly-innocuous phrase as a secret message.
Which brings the question; “Are you a traveling man?”