The superrich secretly detest the group-house yuppies. Families with long claims on ancestral farmsteads privately sneer at hedge-fund nouveaux riches perched in seaside mausoleums. Members of the private clubs at the top of the local social pyramid turn up their noses at the socially unfavored.

And the hard-core surfers, who not only brave the rocky right break at Camp Hero in Montauk but also do it in winter, openly disdain the ankle-leashed newbies who turn up each July at Ditch Plains, noses slathered in zinc-oxide, unblemished boards tucked beneath their arms.

It’s not exactly news that clothes denote status, but in beachside communities, where even corporate raiders and United States senators slope around in flip-flops and board shorts, the signs of inclusion among local elites are more challenging to convey. And, while there is no formalized uniform to identify which group one belongs to, a lot can be read in an item that upon a time was worn as underclothes.

I am talking about T-shirts, of course, like the one from Ditch Witch in Montauk, sold in one place only: a car adjacent to the Ditch Witch food truck, which Lili Adams has operated for the last 15 years in parking lot No. 2 of the famous surf beach at Ditch Plains.

Unlike the generic tourist fare sold along Main Street, sewn in Sri Lanka but blaring MONTAUK, the Ditch Witch T-shirt goes to no particular effort to suggest where or what the Ditch Witch is. Like the Black Dog T-shirt that stood as an insider’s symbol of Martha’s Vineyard until Bill Clinton was photographed wearing one while running (thus propelling the shirt’s silhouetted Labrador logo into the pop cultural mainstream and locals’ own T-shirts into Goodwill bins), Ditch Witch T-shirts telegraph pure insider status to those in the know.