"This was an experiment, right?" said Travis Laurendine, standing in a men's room. "The experiment was, 'What if you could make a company that's so funny that it markets itself?'"
The experiment may be succeeding.
Laurendine co-founded Airpnp, based on the very successful Airbnb, a site which allows people to rent out their homes. In the case of Airpnp, however, people are renting out their bathrooms, hence the 'P.'
"People in the United States take 3 trillion pees a year—3 trillion," he said. "Do the math. Trust me, I have."
Peer-to-peer takes on a whole new meaning.
Here's the backstory. Laurendine is a former comedian from New Orleans who's transformed into a start-up entrepreneur and hackathon host. He just attended South by Southwest. He's even listed on the White House website as a "Champion of Change."
Airpnp started out as a gag during Mardi Gras 2013. Laurendine said friends would tell him, "'I've gotta pee,' and I was, like, 'Well, I'm going to make Airpnp,' and they're, like, 'That's hilarious.'"
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After they stopped chuckling, more than a few friends suggested he really launch the company. Laurendine teamed up with Max Gaudin to make a website and start a social media campaign.
"It just became such a word-of-mouth story, it was out of our control ... I mean, if you go look at it now, we have more people in Europe than even New Orleans with no marketing," Laurendine said. "We have a hundred bathrooms in Antwerp," in Belgium.
Both men are making a little money off the venture by taking a slice of sales from homes and businesses renting out higher-end bathrooms. They hope to soon land a sponsor for the site, saying two toilet paper brands have contacted them, and they plan to have iTunes and Android apps within a year.
After that, Laurendine wants to offer "VIP" service. "The high end is having a bathroom attendant," he said.
One caution: much like Craigslist, there are no background checks on people renting their bathrooms or their customers. "Luckily, you know, we haven't had something go wrong."
As for confusion between his company and the much larger Airbnb, Laurendine said Airbnb asked him to put a disclaimer at the bottom of his website saying his business is not affiliated with theirs, but he added the company told him, "They support the growth of the sharing economy."
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Airpnp got its first test during this year's Mardi Gras, an event where there are never enough public restrooms to meet demand. Laurendine said the business model worked out pretty well. "My friend had three people from Houston come use her bathroom in the French Quarter," he said. They paid $20, "and she went out with them after."
I tested the service while on the road in San Jose, Calif. The website listed a bathroom nicknamed "Ducky's" in someone's apartment, though there was no phone number or email address to contact the owner ahead of time.
I just showed up, and no one was home, except some barking dogs. (I actually needed to use the restroom at this point, so I went where I always go ... Starbucks. I also purchased a beverage as "payment," which probably cost me about the same as renting out someone's toilet.)
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Perusing the list of bathrooms available on Airpnp, many of those in Europe are public bathrooms in parks and restaurants. In the U.S., often people are just joking, though sometimes it's hard to tell. Other times, it's clearly a gag.
So is the whole business a joke? Are reporters being punked? Laurendine said the whole "experiment" is part fun, part real.
"We're actually real entrepreneurs, we solved this problem for ourselves," he said.
Laurendine has high hopes that in a sharing economy, there's room to grow for a recession-proof business like needing a bathroom. "There's a steady stream of customers."
—By CNBC's Jane Wells. Follow her on Twitter: @janewells.