As the kind of guy who doesn’t need any particular item of apparel to get in touch with my inner animal spirit, I was skeptical when my friend Steve and his daughter Dorothy started enthusing about the Three Wolf Moon T-shirt and attendant Internet culture phenomenon. Yeah, right, I thought.

But ... after I put on the T-shirt, immediately grew back all the hair I’d lost decades ago and got a seven-figure contract to star in a kung fu romantic comedy along with Maria Sharapova and Scarlett Johansson, I had to admit I was wrong.

Brian Govern, a 32-year-old law student in Glassboro, N.J., had no idea what he had started when he wrote a similarly over-the-top review on Amazon.com of the T-shirt, which shows three wolves howling at the moon. Employing the snarky spirit of online humor, the review began:

“This item has wolves on it which makes it intrinsically sweet and worth 5 stars by itself, but once I tried it on, that’s when the magic happened.”

The magic, it turned out, was not so much the undeniably totemic power of the shirt, now endorsed by about 700 other similarly rapturous, if not entirely serious, reviewers, but the lesson in the inscrutable power of online culture that it provided. Like the butterfly wings creating the tornado, Mr. Govern inadvertently helped set off an almost impossible marketing bonanza and pop-culture craze: The shirt has been Amazon’s top-selling item of apparel every day since May 19, and it has morphed into one of those instant icons of Internet culture.