A brogue originally meant an Irish accent in the pronunciation of English, but has come to mean any strong regional accent.
In the Book of Judges (12:4-6), 42,000 Ephraimites were massacred when their brogue betrayed their origins. After the Ephraimites were routed by the Gileadite army they tried to retreat by fording the Jordan River at a checkpoint that was held by their enemy. The Gileadites, aware of their plan, asked each soldier who tried to cross if he was an Ephraimite. If the soldier said "no," he was then summoned to say the word “shibboleth” (which means "stream" in Hebrew). Gileadites pronounced the word "shibboleth," but Ephraimites said "sibboleth." Anyone who used a sibilant was executed on the spot.
Shibboleth has come to mean “a catchword or slogan used by members of a group but regarded by others as empty of real meaning b : a commonly held belief .” When English speakers first borrowed "shibboleth," they used it to mean "test phrase," but it has acquired other meanings since that time.