Allen said Pepperidge Farm was so pleased with the stunt that it would "most definitely" do it again.
But brand expert Rob Frankel said he's not so sure about the flash mob idea.
"It's a novelty, and novelties are almost never sustainable," he said.
Frankel's concern is revenue, the Achilles heel for many companies, from Facebook to The New York Times.
"After the top-line hype on the deal, you have to look at the bottom line. Is any of that linked to revenue?" Frankel said.
Of course, there's also the question of how you pay 500 people to wear a shirt—or do you?
(Read more: The best jobs of 2013 ... and the worst jobs)
HeadsetsDotCom wouldn't disclose how much Pepperidge Farm paid for the stunt but said it was "less than $20,000."
He didn't pay the T-shirt wearers but is looking into some type of reward structure in which whoever has the most-shared photo or has made a really great YouTube video would get a gift card or some other giveaway.
And of course, the one question you have to ask is: After five years, isn't HeadsetsDotCom sick of wearing T-shirts?
In fact, no.
The T-shirt business brought him not only a six-figure job, but love.
He met his girlfriend, Caroline Winegeart, in 2010, when she invited him to come and speak at the University of Florida's advertising club. (She was its president.)
A year and a half ago, she joined the company, bringing her artistic and organizational skills. Just a few days ago, they launched their own online T-shirt store, featuring some of HeadsetsDotCom's favorite sayings for entrepreneurs, including "Innovate or Die" and "Fail Fast, Learn Faster," with designs by Winegeart.
"For five years, I got paid to wear shirts. Now I want people to wear shirts I design," he said. "The irony!"
Technically, he retired from professional shirt-wearing earlier this year to focus on other projects. Like being a pro athlete or dancer, being a T-shirt wearer takes a toll, he said.
"Five years was all my body could handle—my shoulders are gone!" HeadsetsDotCom said.
The real irony, perhaps, is that in an age of big data, where machines do everything from order us dinner to trade stocks, this big idea is all about the humans.
Until you can coordinate a flash mob of monkeys to wear shirts and tweet, there's some job security for us humans!