A shibboleth is a word that some people pronounce in a characteristic way, so they can be recognised by listening carefully. The word goes back to the Bible, Judges 12: 6, (King James Bible "Authorized Version", Pure Cambridge Edition) that reads:
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.
Many other shibboleth-episodes happened in the course of history: Between September 28 and October 8 1938 the Generalísimo Rafael Leónidas Trujillo, at the time dictator of the Dominican Republic, had his army kill around 15.000 of migrant Haitian sugar cane workers. Because the Dominican Republic has such a diversity of racial types living in harmony, the Haitians were identified for murder by their inability to pronounce the word "perejil" (Spanish for "parsley."). Some histories refer to this as The Parsley Massacre The river where the bodies were dumped was known as Río Dajabón and fixed the frontier between the Dominican Republic and the Republic of Haiti, it is now aptly known as Rio Masacre (Massacre River.)
Germans are apparently unable to pronounce the English word “squirrel”, or so is claimed: This could come in handy if ever Germans have to be identified (if suspected of spying, for instance. Or of Rechthaberei, if that in itself does not give them away).
But the point is: there is no translation of this word into Spanish or German. Despite the fact that both languages have a thorough Bible tradition. They should know the word, to be prepared against the concept lurking beneath.