Mountain Dew” was originally a slang term for moonshine.

Mountain Dew” was originally a slang term for moonshine.

Mountain Dew" was originally Southern and/or Scots/Irish slang for moonshine (i.e., homemade whiskey). Using it as the name for the soda was originally suggested by Carl E. Retzke at an Owens-Illinois Inc. meeting in Toledo, Ohio, and was first trademarked by Ally and Barney Hartman in the 1940s.

Mountain Dew" is a centuries-old mountain slang term for moonshine ... initially crafted as a mixer for whiskey in the early 1930s.

Mountain Dew was originally developed as a mixer for whiskey

 Long before it became a soda, the term "mountain dew" was a nickname for moonshine. ... The brothers jokingly named the beverage Mountain Dew after the term's nickname, joking that it tasted just like moonshine when mixed with liquor.