Earlier this summer, on a beach in Santa Cruz, the big-wave surfer Shawn Dollar took a swig from a magnum bottle of champagne and hoisted a trophy in the sun. Dollar has a couple of Guinness World Records to his name, which he got by paddling into monstrous waves over fifty-five feet tall, rides he pulled off on an ultra-stiff, hand-shaped, gun-style surfboard. But on this day in early July he was celebrating his victory in the Wavestorm World Championship, a contest he won in two-foot surf atop the Wavestorm Classic Longboard, a soft surfboard that sells for a hundred bucks at Costco.

Dollar founded the soft-top-surfboard-only contest with a couple of other surfers in 2015, as kind of a gag. Despite its name, the championship is not affiliated with AGIT Global, the company that manufactures Wavestorm boards, or with Costco. (It was formerly called the Kirkland Classic World Championships, in a kind of mocking honor to Kirkland Signature, the Costco house brand that labels everything from vitamins to bacon to gasoline.)

There are no rules at the Wavestorm World Championship, which is part demolition derby, part beach party. (Dollar said that most of the hundred or so surfers were pretty buzzed.) It’s also a sendup of the surfers who tend to ride on Wavestorm boards—“kooks,” or surf newbies, who don’t necessarily know or follow the sport’s tacit codes. Really, though, the event gives experienced surfers an excuse to have a blast breaking those codes themselves. To win, Dollar said, he did everything you’re not supposed to do in a surf contest: steal waves, make contact with other surfers, and “create a general mess in the water.” In one heat, he pushed a surfer wearing angel wings into the whitewash. “No matter who you are, when you ride a Wavestorm, you’re a kook,” Dollar told me. “I don’t know, I kind of like being a kook.”

Though it has been nipped, tucked, and stiffened over the years, the Wavestorm eight-footer has existed in roughly the same form since 2006. That’s when Matt Zilinskas, a former manager of the Boogie Board brand, and the Taiwanese businessman John Yeh, of AGIT Global—Boogie Board’s manufacturer—tweaked AGIT’s sandwich of expanded polystyrene foam and plastic to create a board for a surfer’s “first standup experience.” The Wavestorm, a high-volume, low-profit-margin play, was priced at a third of what most starter surfboards cost. By 2015, Bloomberg Businessweek reported that over half a million Wavestorms had been sold, and Costco was on pace to sell a hundred thousand that year alone. (Zilinskas calls those numbers “outrageous” but declined to provide more accurate figures.) In peak summer, they can be bought at nearly two hundred coastal Costco locations.

Though pro surfers like Jamie O’Brien have taken Wavestorms on some of the world’s most dangerous breaks—such as Oahu’s Pipeline—as a kind of humblebrag, the board is not perfect. Surfers note that it soaks up seawater with time. At high speed, its plastic fins chatter. Its leash is tangle-prone. Compared to the carbon-fibre-wrapped shortboards currently championed by surf shops and ridden in high-level competitions—boards that slash up and down a wave’s face, building speed like a Scuderia Ferrari—the Wavestorm moves more like a school bus. But it is very good at catching waves. Maybe too good. “It’s possible to get greedy on one,” Gary Linden, a surf shaper and co-founder of the Big Wave World Tour, a triannual contest held in thirty-foot-plus waves, told me. He cites the board’s float, its paddling ease, and its drive through the water.

Surfers call the Wavestorm a Costco Cadillac, a sofa, or a bath toy. “If I’m in really good waves and someone paddles out on one, it means they most likely don’t know what they’re doing,” Dollar said. Such riders may endanger others by not knowing where to paddle out; they might ignore a break’s pecking order, “dropping in” on a wave where another surfer has priority. Matt Warshaw, the author of “The Encyclopedia of Surfing,” called the antagonism toward Wavestormers “just the latest misguided frustration for surfers, who are always pissed off,” and said that it resembled the scorn that surfers had in the eighties for bodyboarding, then experiencing a boom. “You saw prime breaks like Off the Wall, on the North Shore, become nearly overtaken by bodyboarders,” he said. “It was like the killer bees were coming. You’d think there was going to be a civil war.” A commenter on Surfer magazine’s Web site, meanwhile, recently promoted stoic forbearance. “The Wavestorm phenomenon will pass,” he wrote. “We lived through ‘Gidget.’ We’ll live through this.”

The Web is where the Wavestorm phenomenon has been most thoroughly documented. The Instagram account the Kook of the Day, which has over half a million subscribers, compiles surreptitiously snapped photos and footage of neophytes committing various style errors and surfing sins. In one shot, a Wavestormer wears board shorts over his wetsuit; in another, a person riding a hoverboard drags the tail of his Wavestorm though an intersection. One Kook of the Day staple is a shot of Wavestorm boards hastily shoved through the sunroof of some sedan, splayed like pickup sticks. A number of videos show Wavestormers face-planting in foot-high surf.

But not all social-media fodder over the Wavestorm has been as barbed. The Instagram account Team Wavestorm Official—which, despite its name, is not affiliated with the brand in any way—has more than twenty-three thousand followers, and enthusiastically cheers on Wavestorm riders, whom the account’s creator, Nate Rohner, calls “the outcasts of surfing.” There are photos of locals riding the budget boards on the thunderous waves of Makaha, a surf break near an economically depressed town in Oahu, and there are surfboard selfies taken by Mike Coots, a shark-attack victim who surfs on a Wavestorm because his prosthetic leg would damage a fibreglass board. There are also clips of “groms,” or young surfers, launching off of their Wavestorms into acrobatics, in pounding, otherwise unsurfable shorebreak. Team Wavestorm’s Instagram isn’t about high performance so much as sheer invention. “In my opinion, the Wavestorm brought a carefree feeling back to surfing,” Rohner said. He created the account while he was at school in Utah, six hundred miles from his home break in San Diego. He recently graduated, and is about to begin his first job post-college. A few weeks before he starts, he’s going to run a surf contest in Laguna Beach. Wavestorms only.