In ancient times, the Bible recounts (Judges 12: 4-6, for you scholars), a war broke out between the Ephraimites and the men of Gilead, and the Ephraimites, defeated, attempted to cross a river ford held by the Gileadites. “[W]hen those Ephraimites which were escaped said, ‘Let me go over’ the men of Gilead said unto [each], ‘Art thou an Ephraimite?’ If he said, ‘Nay,’ 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.”
“A shibboleth is a word, sound, or custom that a person unfamiliar with it … does not pronounce or perform correctly as perceived by those who are familiar with it.” It can therefore identify those who do not belong to a particular nation, class or group of people. (My definition is Wikipedia-improved-upon). In the case of the Ephraimites, they spoke the same language as the Gileadites, but their inability to pronounce “sh” evidently resulted from the fact that the tribes had lived in different regions for some time. Forty-two thousand is an awful price to pay, and I suspect the test was not carried out under what might be called “clinical conditions.” Based upon a similar shibboleth test, it appears that thirty thousand people suspected of being trespassing Haitians were killed by Rafael Trujillo in 1937.
During World War II, shibboleths were used to identify suspected infiltrators. For example, unknown persons approaching a guard post in the Pacific theater of war were challenged and told to pronounce the word “Lollapalooza.” If they said “Rorraparooza,” they were likely to be shot forthwith, since the Japanese could not handle the “el” sound. In 1923 the Japanese had themselves used the shibboleth of ba bi bu be bo to distinguish ethnic Koreans from Japanese, as it was assumed that Koreans would be unable to pronounce the line correctly. All people who failed the test were killed with great cruelty and wrong being done in the process.