title_body: Origin of the "lick, sip, suck" tequila shot technique
upvoted_answer: This article does not reference any date, but says something interesting:
  
  
    Mexicans have long known that a little sodium chloride on the tongue can help to mollify the fiery flavor that characterizes much of their food. They use salt when downing chile peppers, for example. By the same token, citrus juices of various kinds have long been used to kill the aftertaste of the more potent forms of alcohol [...] Anyway, when tequila came to the U.S., the salt and lime (or lemon) bit came with it.
  
  
  Further, Stanford University Press Blog states that salt and lime were used to mask bad tequila:
  
  
    Legend holds that the origin of serving salt and lime with tequila evolved as a response to an early tequila “boom” in the late 19th-century. The unpredicted spike in popularity led to a proliferation of poor quality tequila brands; salt and lemon were used to mask the taste of crudely-made tequila. Unpleasant or not, the ritual remained and soon became a familiar feature throughout Mexican popular culture.