4:20 pm on 4/20/2012 in Denver, Colorado. | Marc Piscotty/Getty Images

It’s not police code for smoking weed.

The number 420 holds a God-like place in stoner culture. In a country where someone gets arrested for weed every 51 seconds, those three little numbers are a simple, subtle way to check if someone’s cool with cannabis.

But where did it come from? Over the years, people have claimed “420” is the number of chemical compounds that cannabis buds contain. Others have said it’s the police code for a marijuana-possession crime. The debunker site Snopes has disproved many of these wacky-tobbacky theories, but you know how people are. They just don’t listen to truth.

So let’s delve into the real story, which takes us back to 1971 in Marin County, California. A group of five high school kids — who called themselves “The Waldos” because they used to hang out next to (you guessed it) a wall — were searching for a hidden marijuana crop in the forests near the town of San Rafael.

StefanieLislSaathoff/Getty

According to the Huffington Post, which has done some of the most diligent research into this extremely important issue, a Coast Guard member told the Waldos that he’d planted some weed near the Point Reyes Peninsula Coast Guard station that he couldn’t harvest. He gave the Waldos a map and told them the pot was theirs if they could find it.

The Waldos jumped at the chance to find free weed. They decided to meet after school — at 4:20 pm, to be exact — at a nearby statue of Louis Pasteur. There, they’d smoke up before driving out to the forest to search for the illicit crop.

One of the Waldos, who calls himself simply “Waldo Steve,” told the Huffington Post that the group started referring to these secret meetings with the code “Louis 420.” Eventually they stopped saying the “Louis” part.

Obviously, it takes more than a few high school stoners to turn “420” into an international phenomenon. According to the Huffington Post’s reporting (which you really should read in full), the Waldos’ had friends and family members who used to hang out with the Grateful Dead. Eventually, members of the Dead and their entourage started saying “420” to refer to weed. As the band played hundreds of concerts a year all over the world in the 70s and 80s, the term spread.

In 1990, a Deadhead handed a flyer to High Times reporter Steven Bloom that repeatedly used the term “420.” Soon, the magazine began using the phrase, too. High Times is probably responsible — at least in part — for pulling the term from Grateful Dead subculture and making it mainstream.

Sadly, the Waldos never found their mythical crop, but their contribution to worldwide stoner culture is infinitely more lasting than a couple weed plants in a Marin County forest could ever be.