If you smoked weed in college (you did), you probably had a run-in with a guy wearing a drug rug. The drug rug (a.k.a. Baja hoodie) is worn by all sorts of stoners, from Dave Matthews Band fans, to Phish heads, to Wiz Khalifa stans, from joint rollers, to bong-rippers, to hot-boxers. After staring at these colorful heavy sweaters enough times, trying to find the meaning of life in its distinct pattern, you may have asked yourself about the origins of the drug rug. Wonder no longer: Here’s how the drug rug came to be.

The term “Baja hoodie” isn’t some marketing creation: The drug rug was actually popularized in Baja, Mexico. Locals, inspired by the thick blankets (called “jergas”) they had been using for generations, took the the fabric and bold patterns and fashioned hooded shirts out of them. While there is evidence that Central and South American cultures have been using jergas as blankets and even as ponchos since the 1300s, the long history of the jerga collided with California youth culture in Mexico in the ’70s. Surfers noticed the thick sweaters when on trips to Mexico, after making their way down the coast chasing the best waves. As adventurous surfers brought the shirts back from Baja, many young counterculture Californians saw the pullover sweaters as an opportunity to let their freak flag fly. Mexican locals saw an opportunity to push a must-own souvenir on American visitors. Called a “sudadera de jerga” in Spanish, the drug rug proved to be perfect for barechested surfers to throw on as the beach day gave way to a chilly night.

The legend of the drug rug grew from there, as what began as a counterculture item grew into a national craze. As the ’70s wore on, the Baja hoodie came to stand in for West Coast drug culture. As that culture, which has been romanticized since the days of hippie communes in Topanga Canyon and mind-expanding spiritual retreats to Big Sur, continued to capture the American imagination, sales skyrocketed. The legend of the Baja hoodie grew to be so synonymous with drug culture that people began to believe the shirt was made of hemp, even though it is usually is made of a cotton blend. (This point has been further confused because they are sometimes made of hemp today.)

The popularity of the drug rug grew even more in the ’80s, as mainstream culture adopted the hoodie as a stand-in for stoner culture. Sean Penn famously wore a Baja hoodie in his portrayal of stoner hero Spicoli in Fast Times at Ridgemont High. Luke Perry’s Beverly Hills, 90210 character, Dylan, also wore drug rugs, as the writers sought to tie him to California cool. By the ’90s, the drug rug became an easy symbol of a particular lifestyle and an aspirational item for teens who longed for a laid-back coastal lifestyle while stuck in a landlocked suburb. Like tie-dye and bandanas, the drug rug was now forever a part of stoner iconography.

Like most counterculture pieces that catch fire and gain broad style cache, certain takes on the drug rug have landed on the runway and commanded a ridiculous price tag. Fashion industry observers have noted Baja hoodies selling at over $2,000 a piece, as ’70s styles came back into fashion and marijuana lifestyle gear has gained traction with the renewed push for legalization. Along with bell bottoms and leather jackets, the Baja hoodie is now part of the American culture, and will likely see continued recycling, repurposing, and reconsideration as the years march on and America’s relationship with drug culture continues to evolve.