Oh du lieber Augustin
means Oh, my dear Augustin
Augustin, also known as "lieber Augustin" was a street singer in Vienna in the 17th century. The tale about him is that one day when coming from an inn he fell asleep in streets. That was in the time of the great plague and many people even died in the streets. The corpses were collected on carts and brought outside the town to be buried in "Pestgruben = plague holes" which were mass graves. Augustin was believed to be dead, stoned as he was, and put onto the cart and put into the "Pestgrube" next morning he woke up and shouted and played his bagpipe until he was put out again. (the grave had not been closed of course as it was not yet full). The legend is that he never fell ill with the plague - many people say the alcohol did protect him.
Oh, du lieber Augustin is a popular folk song (not a children's song) from the beginning of the 19th century.
Austrian, we read his story in primary school