It's not just a Scottish thing, he's also the patron saint of Cyprus, Greece, Romania, Russia, Ukraine, Bulgaria, the Ecumenical Patriarchate of Constantinople, San Andres Island in Colombia, the parish of Saint Andrew in Barbados and Tenerife.
"You, boy, what day is it?"
"Why it's St Andrew's Day!"
"Then take this sixpence and buy me the biggest square sausage you can find."