(Reuters) - Don't get into a pissing match with walls in San Francisco.

The city's Public Works agency is testing a pee-repellant paint on walls in areas that have been saturated with urine. Anyone urinating on the specially treated walls will get the spray splashed back onto them.

San Francisco's director of public works, Mohammed Nuru - whose Twitter handle is @MrCleanSF - got the idea when he read on social media about the use of the paint in Hamburg, Germany's nightclub district to stop beer drinkers from relieving themselves in the street.

The paint, called Ultra-Ever Dry, is sold by Ultratech International Inc and is billed as a superhydrophobic coating that will repel most liquids.

"The urine will bounce back on the guys pants and shoes. The idea is they will think twice next time about urinating in public," said Rachel Gordon, a Public Works Department spokeswoman. She said the super-hard coating made the "bounce back" effect much stronger than when peeing on a regular wall.

In a pilot program, San Francisco last week painted nine walls in areas around bars and other areas with big homeless populations.

"Hold it! ... seek relief in an appropriate place," say signs posted near the paint. The signs are in English, Chinese and Spanish.

The paint went up just last week, but the city is already getting requests for more.

"We've gotten many, many calls from people who wanted it done in their alley or on their buildings," Gordon said. "Some people are saying it's just a gimmick, but other people hope it will combat some of the smelly areas of San Francisco that have been saturated with urine."

The cost of painting the walls is much lower than sending out workers to steam clean areas, she said. The city gets hundreds of requests a year to clean up urine.

The city has also added public toilets to reduce the urine problem, Gordon said.

(Reporting by Fiona Ortiz in Chicago; Editing by Steve Orlofsky)