You've seen the memes of red-eyed Snoop Doggs and tie-dye-clad hippies. You've heard the anthems by Kid Cudi and Afroman. You might have even witnessed the annual cloud of dense smoke that falls over your local park or college campus every April 20th.

No matter what your proclivities are, a day dedicated tosmoking Mary Jane is surely a sight to be seen. So what's the deal with this unofficially recognized holiday? Why is 420 Weed Day a thing? Let's take a look at its history and how it became the de facto day of celebration for stoners around the world.

What is 420?

The meaning of 420 is quite simple: it's a code for April (the fourth day of the month) 20th, or 4/20. For reasons not entirely known, this number and date are associated with cannabis culture.

While it used to be a fringe holiday celebrated only by hardcore stoners, it's risen to mainstream notoriety over the past few decades. Denver's Mile High 420 Festival draws in around 50,000 people each year, while San Francisco's annual 420 celebration on the aptly named Hippie Hill attracts around 20,000. There are concerts, t-shirts, and all sorts of pot-related paraphernalia to purchase as organizations clamor to commercialize and capitalize on this now-popular "holiday."

So how did this relatively innocuous code become such a famous rallying cry for cannabis users around the world?

How Did The 420 Day Come About?

The origin of the 420 code is unclear, but there are a few strange theories floating around.

Some say that it's a reference to the police (the California penal code for weed is 420) or the number of active chemicals you'll find in marijuana. But that's false; there are 480. Others claim that it's a play on the English tea time, which typically happens at 4:20 p.m. Back in the day, "tea" was slang for Mary Jane.

And perhaps the most complex—and far-stretched— is the theory that it was derived from the infamous Bob Dylan line "Everybody must get stoned," which is from his hit "Rainy Day Women #12 & 35." When you multiply 12 by 35, you get 420. 

This last explanation might hold some water,  though. According toHigh Times editor Steven Hager, 420 was started in 1971 by a group of high school students in San Rafael, California, who were given a map to find a patch of weed grown by a U.S. Coast Guard who was afraid of getting caught. These students—who called themselves "The Waldos"—agreed to meet at 4:20 p.m. to get high and go find the patch.

They never found that patch, but after that day, they used 420 to refer to weed in general, and the code quickly caught on with their peers. To this day, they maintain that they were the first to use the code. They even have some documentation stored away in a bank vault to support their claim—though nothing is 100% certain.

Regardless of its origins, 420 has become a rallying cry for weed smokers across the globe. It's a day—or a time—to come together, spark up, and celebrate all things marijuana.

What Does 420-Friendly Mean?

The number 420 has evolved beyond signifying a date or time. It's also come to represent a certain lifestyle and set of values.

When you see a business or event that's advertised as 420-friendly, it means that they're open to and tolerant of cannabis use. This could be a dispensary, a head shop, a cafe, a music shop, or even a rental property. More and more businesses are advertising themselves as 420-friendly as cannabis becomes more mainstream—and more legal.

People have also taken a liking to the term 420-friendly to describe themselves. If you see someone label themselves as 420-friendly on a dating app or on social media, it usually means that they dabble in cannabis use and are open to interacting with others who are as well.

However, what 420 means can be different from person to person. So if you see someone advertise themselves as 420-friendly, make sure to ask what that actually entails before you start making assumptions.

In essence, seeing "420-friendly" gives you the okay to toke up without judgment, stigma, interference, or penalty. However, you should always brush up on the local laws before indulging. Just because a person or a business is 420-friendly doesn't mean the government is.

What Will Happen to 420 If Cannabis is Federally Legal?

Now that cannabis is legal in 21 states—with more on the horizon—it stands to reason that the feds will eventually catch up and make marijuana use legal across the country. If (or when) this happens, what will happen to 420?

Most likely, we'll continue to see a trend of commercializing and normalizing the holiday. Big brands will launch 420-themed products and events, while pot shops will offer special discounts and promotions. There will be more and more festivals (likely charged, not free as they've historically been), and more and more people will partake.

Cannabis is already a billion-dollar industry, which makes the incentive to turn 420 into a money-making holiday all the greater. So while the underground, alternative culture of cannabis might not be too keen on this idea, those with a more business-minded approach will likely jump at the chance.

Having major corporations get involved could also help to legitimize the holiday and make it more mainstream. But it could also water down the rebellious, counter-culture image that many stoners are attached to. Not to mention,  it could price out those who can't afford to partake.

So while the future of 420 is hazy, one thing is for sure—it's not going anywhere anytime soon. As long as there are people who enjoy smoking weed, there will be a need for a day to celebrate it.

Whether you choose to spend your 420 at a corporate-sponsored festival or in your own backyard, the most important thing is that you enjoy it. Light up a joint, relax, and let the good times roll.