HAPPY 4.20 🌿 The Origins of 4/20: From High School Code to Global Symbol Every year on April 20th—better known as 4/20—millions of people around the world celebrate cannabis culture. What many don’t realize is that this global phenomenon started as a simple inside joke among a small group of teenagers in California. The most widely accepted origin traces back to 1971, when five high school students in San Rafael, California—nicknamed “The Waldos”—used “420” as a secret code.