Ah, 420. Like most things intimately connected to the smoking of marijuana, the origin of the pot-friendliest number in the world is hazy and frequently has the munchies.

As myth-busting website Snopes.com makes clear, myths about 420’s genesis and meaning abound. Among the mythic frontrunners: It’s the penal code for marijunana use in California! (Nope—Section 420 of CA’s penal code deals with obstructing entry to public land.) There are 420 chemical compounds in marijuana! (Nope—according to High Times, there are 315.) It’s Jerry Garcia’s birthday! (Nope, he was born on 8/1.) It’s Jerry Garcia’s death-day! (Nope, he died on 8/9.)

As it turns out, the most well-supported 420 creation myth is also the most interesting. From Snopes.com:

‘420’ began its sub-rosa linguistic career in 1971 as a bit of slang casually used by a group of high school kids at San Rafael High School in California. ‘420’ (always pronounced “four-twenty,” never “four hundred and twenty”) came to be an accepted part of the argot within that group of about a dozen pot smokers, beginning as a reminder of the time they planned to meet to light up, 4:20 p.m. Keep in mind this wasn’t a general call to all dope smokers everywhere to toke up at twenty past four every day; it was twelve kids who’d made a date to meet near a certain statue.

And that’s how a bunch of high-school stoners from California came to influence American slang.

For more on the cult o’ 420, check out the Wikipedia listing, especially the freakishly thorough section on 420 references in popular culture.