In the culture of cannabis, April 20 is a holiday when those who partake light up in enjoyment and in protest of prohibition. Although the origins of “4/20” are debated — according to popular lore, a group of California high school students in the 1970s met after school at 4:20 p.m. to smoke weed — the day has been globally celebrated for years.
https://www.nytimes.com/2024/04/20/nyregion/420-weed-celebration-sponsor.html