When I met with Josh Hartnett in his hometown three years ago to profile him for this magazine, here’s what he was wearing: a T-shirt over a long-sleeved thermal undershirt.

And here’s what I was wearing: a T-shirt over a long-sleeved thermal undershirt.

You could chalk up the fact that we were wearing the same thing to, say, the need to layer in Minneapolis in the dead of winter. Or you could chalk it up to a failure of imagination—on my part, that is. Josh Hartnett, at least, was wearing what he was wearing because he’s Josh Hartnett; this was his look. I, on the other hand, was wearing what I was wearing because of . . . Hartnett.

Well, make that Hartnett, et al. Because the look I’d subconsciously internalized had been championed not only by him, of course, but also by a whole continuum of celebrity guys. Step back a few years, swap out the T-shirt for some plaid, and you’ve got the layered grunge look of Eddie Vedder & Co. Fast-forward to the present day and channel-surf for 10 minutes and you’ll see the current variation all over the dial. There’s Seth, on The O.C., in a tee over a long-sleeved tee. (And wasn’t Ryan wearing the same thing right before the commercial?) Over on MTV, there’s rapper Xzibit hosting Pimp My Ride, in a tee over a long-sleeved tee. The guy whose ride he’s pimping? He’s got on, yes, you know what. It’s officially omnipresent. “You see it in the winter,” says Mark-Evan Blackman, the chairman of the menswear-design program at the Fashion Institute of Technology in New York, “and you see it in summer, which is insane.”

And the problem isn’t just one of flouting temperature, but that the shirt-on-shirt business doesn’t work for your average desk jockey. “It’s a sleek look,” says Blackman, “which is interesting, because a lot of today’s youth isn’t sleek. It becomes a bad idea when you’re looking over your stomach.”

The outfit originated among practical Southern California surfers, yet many of the whales now wearing it are farm-country heartlanders. Back in Minneapolis, Aaron Keller, a founding partner of the design and marketing company Capsule, thinks the thermal version of the look is about “showing something personal—your undies—to offer a glimpse of you as an individual.” And since the thermal (or long-sleeved) shirt is invariably paired with a blank or obscure tee on top, the idea is to show an image that’s “not mass retail and not mass-branded.”

Fine. But what happens when anti-brand becomes a brand statement of its own? What happens when anti-fashion becomes fashion—a mandated look, even a runway look? Paul Smith, Dsquared, Byblos, Burberry, Missoni, Prada, Etro, Iceberg, and Mark Ecko have all shown it recently. The real problem is this: You leave the house in the morning thinking, I’m wearing what’s comfortable, what’s low-key and authentic. But it turns out you’re really just an unwitting slave to the celebrity-enabled fashion Zeitgeist.