How Apirl 20 became 'Weed Day' ?

April 20 (or 4/20) is cherished by pot smokers around the world as a reason to toke up with friends and massive crowds each year. Major rallies occur across the country, particularly in places like Colorado and California, where marijuana is legal.

The 4/20 celebrations have taken off in the last few years, but their origins appear to lie in the escapades of a group of friends from San Rafael high school, northern California, in 1971. That autumn, the five teenagers came into possession of a hand-drawn map supposedly locating a marijuana crop at Point Reyes, north-west of San Francisco. (from CNN)