While "tipple" is a word of English origin, "gratis" is the Spanish word for "free;" therefore, "tipple gratis" is the same as "free tipple." "Tipple" has various meanings in the English language.
A tipple can refer to the apparatus used for unloading the contents of a mine cart into railroad cars. A tipple can also refer to a Spanish guitar-like instrument. "Tipple" is also a slang word that can refer to any alcoholic beverage. "Tipple" is occasionally used as a related verb meaning to drink alcohol regularly but not excessively, or with the meaning of putting hay in bundles for the purpose of drying it.