The first time I walked up to the yellow house on the corner of Southeast Stark Street and 26th Avenue, I had to pee. 

The door was ajar. When I knocked, only a dog answered. A sign on the wall read, “Loud sex is fun.” 

I had come to this two-story home because its occupants had listed their bathroom as open to the public, for a fee ranging from $1 to $5. "Small, calm, space, with good company and a cat,” the listing reads. 

The home's bathroom and two others in Portland are listed on a new Web app called Airpnp. 

Instead of renting lodging, users locate the nearest private bathroom whose owners are willing to welcome strangers—in exchange for payment.

Airpnp's website says, "When there aren't enough bathrooms nearby for the amount of people in any given location, Airpnp is there to save the day."

I had more luck at another listing on Southeast Belmont Street, at a business called Nemo Design.

The Nemo Design team was welcoming, and the firm's restroom had a nice wallpaper décor. According to the listing on Airpnp, visitors could use the restroom, stocked with toilet paper, individual stalls and two sinks, all for $16.95. 

Jessica Raddatz, the company's art director, says she recently found Airpnp on a music site and thought it would be funny to list Nemo's restroom.

"We are happy to be early adopters," Raddatz says. "I don't know how many people in Portland know about it, but hopefully more places will sign up.” 

Portland Center Stage, in the Pearl District, is the third Portland location on Airpnp, although a theater spokesman says he's not sure how that happened.

"This is a public space," Center Stage's James Dixon says. "People are welcome to come here and use the bathrooms."

Carol McCreary, who co-founded PHLUSH, a public toilet advocacy group in Portland, says Airpnp shows the need for public restrooms but raises issues of fairness. 

"This website shows that people are willing to pay, but what about the people who can't pay and will be refused access to those private toilets?" McCreary says.

Portland's Downtown Clean and Safe cleans downtown public restrooms and responds to cleanup calls.  A spokesperson for Portland Business Alliance says in the last six months, Clean and Safe workers have responded to 9,500 calls related to human waste—including vomit, blood, feces and urine. 

"We have a huge problem with public defecation," McCreary says. "People don't like to talk about it."

Airpnp founders Max Gaudin and Travis Laurendine, both raised in New Orleans, created the website after getting caught short during a Mardi Gras parade. (Neither Gaudin nor Laurendine responded to requests for an interview.)

The Airpnp site lists 410 available restrooms around the world—92 in the United States, including 30 locations in the apps' birthplace, New Orleans. Belgium has 123.

I returned to the house at 26th and Stark three times—no answer. On one trip, my full bladder and I went to the basement apartment, and a man answered. He said he didn't know where the upstairs occupants were. He hadn't heard of Airpnp. But he offered to let me use his bathroom. 

I declined. 

[Go here for a story about the City of Portland dealing with Airbnb's gray-market guesthouses.]