Origins
A group of people in San Rafael, California, calling themselves the Waldos because "their chosen hang-out spot was a wall outside the school", used the term in connection with a fall 1971 plan to search for an abandoned cannabis crop that they had learned about,based on a treasure map made by the grower.
The Waldos designated the Louis Pasteur statue on the grounds of San Rafael High School as their meeting place, and 4:20 p.m. as their meeting time.[6] The Waldos referred to this plan with the phrase "4:20 Louis".
Several failed attempts to find the crop eventually shortened their phrase to simply "4:20", which ultimately evolved into a codeword that the teens used to mean marijuana-smoking in general.
