Two bottles stand on a parked car outside a university gate. Photo: Sina Weibo user Zhumadianweizhibo

A university in North China's Tianjin garnered attention after campus security said people were soliciting prostitutes outside its gates by placing beverage bottles on their parked cars to signal how much they're willing to pay, Modern Express reported on Wednesday.

Although the school later said no students have taken up their offers, Sohu News reports the method as being used near other campuses in China.  

Officials with Tianjin Normal University (TNU) first issued a warning to students in December 11 detailing the phenomenon and that campus security has been patrolling for suspiciously parked cars. 

"Car owners place bottled drinks on their roofs seeking to solicit prostitution from female students," read the notice on the university's website posted December 11. "Different brands stand for the prices they are willing to offer," the notice read.

The notice, which also described the legal punishment for prostitution in detail, was removed after it went viral.

"What we said in the notice might lead to a misunderstanding," a said an employee with TNU publicity department. 

"We've discovered suspicious cars like this in the past, and brought the owners in for questioning. They admitted to their intentions," said an employee with TNU publicity department, claiming that it hadn't happened since. "Otherwise, we wouldn't have allowed security to post about it. When we find cars like this, we ask them to leave."

Using beverages as signals for prostitution has been reported near other college campuses, according to Sohu News.

Uploaded photos show several luxury cars parked outside school campuses with beverage bottles conspicuously displayed on their roofs.  

The Sohu report relays the code in detail: bottled water signals 200 yuan; green teas stand for 300 yuan; red bull cans are 600 yuan. The most expensive is a can of coconut milk at 1,500 yuan. 

An interested student would remove the beverage and enter the vehicle. If the john is not satisfied, he simply has to say "I'm waiting for somebody else," according to Sohu News.

The TNU employee, however, described the notice as "routine" and was surprised by the attention it generated. 

"Security posts notices like that often… this was just part of our routine work on campus. I never thought it would attract so much attention online," said the TNU employee.

"What we can guarantee is, we haven't had any students get into such a situation. And we haven't had the problem since."

"We don't know why this suddenly got attention weeks later," the employee added, according to Modern Express.