[He] taught me the true cry or masonic word of donkey-drivers, ‘Proot!’1879 June, Robert Louis Stevenson, Travels with a Donkey in the Cévennes, London: C. Kegan Paul & Company, →OCLC, page 18:
The window is handed in [to a wicker carriage]. Her feet are wound around with comforters against a draft... Her ample bag of knitting is safe aboard... Proot! The donkey starts.1917, Charles S. Brooks, There's Pippins and Cheese to Come, New Haven, Conn.: Yale University Press, →OCLC, page 38: