The restaurant, like all Riyadh eateries, has taken precautions to prevent its male and female diners from seeing or contacting each other.
Circular white walls surround each table in the family section, open only to women alone or women accompanied by close male relatives. Other male diners are on lower floors. Yet despite the barriers, the men and women flirt and exchange phone numbers, photos and kisses.
They elude the mores imposed by the kingdom's puritanical Wahhabi version of Islam -- formulated in the 18th century -- by using a 21st century device in their mobile phones: the wireless Bluetooth technology that permits users to connect without going through the phone company.
"It's more fun coming to a restaurant these days," said Mona, 21, as her two friends giggled. Their Bluetooth-enabled mobile phones rested on the table next to the remnants of a dinner of club sandwiches and fries.
"I've been using Bluetooth since it came out last year. We're always looking for new things to add a spark to life," Reem, 24, told The Associated Press.
The women would not give their full names when talking about communicating with the opposite sex -- so strong is the taboo in this kingdom where men and women are strictly segregated.
Unrelated men and women caught talking to each other, driving in the same car or sharing a meal risk being detained by the religious police.
But connecting by Bluetooth is safe and easy. Users activate the Bluetooth function in their phone and then press the search button to see who else has the feature on within a 30-foot range.
They get a list of ID names of anyone in the area -- names, mostly in Arabic, often chosen to allure: poster boy, sensitive girl, lion heart, kidnapper of hearts, little princess, prisoner of tears. Some are more suggestive, like "nice to touch" and "Saudi gay club."
Users then click on a name to communicate with that person.
The phenomenon has started to receive attention in the media, especially after stories appeared saying women were photographing female guests in revealing evening gowns at weddings -- which are segregated -- and circulating them to friends by Bluetooth.
That created some panic among those who feared pictures of their mothers, sisters or daughters would be seen by men. Some families hired female guards to confiscate camera-equipped mobile phones from wedding guests.
There is little the government can do to control Bluetooth use. Last year, it banned camera-equipped phones, but backed off because cameras have become a feature in most phones.
Abdul-Aziz al-Aseeri, a 25-year-old computer science teacher, said he tells his students that Bluetooth technology can be misused. "I warn them of the dangers of having pictures of their mothers and sisters ending up in the phones of their classmates," he said.
But for many Saudi youths, who have almost nowhere to meet members of the opposite sex, the technology is a godsend. It is replacing a favorite method of flirting: throwing phone numbers at women through car windows or in shopping malls.
With Bluetooth, men and women can safely flirt at malls, restaurants and even traffic lights.
For the most part, the messages are innocent. But for this conservative society, it is pretty bold stuff.
Many images feature babies -- some blowing kisses -- perhaps because women consider them cute. Animated cartoons doing bellydances, dreamy Arabic songs and sappy, sentimental messages are also popular.
"Last night I sent an angel to watch over you, but he came back soon," said one message. "I asked him why, and he answered, 'Am not allowed to watch over other angels.'"
Some are more forward: a picture of a woman covered in a cloak and then another one of her in a white top, looking coquettishly from beneath the rim of a cap; an image of two women kissing; a woman taking off her trousers while suggestively shaking her hips.
A few contain hardcore pornography or viruses that infect people's phones.
On a recent warm night, Abdullah Muhammad sat in front of his laptop at a sidewalk cafe waiting for his computer's Bluetooth to pick up nearby users.
"I use Bluetooth to meet girls," said the 24-year-old businessman. "The religious police cannot catch me."
His long, dark hair combed back, Muhammad said when he sees a woman walking past, he presses the search button in the hope her phone's Bluetooth is on.
With women forced to cover up in the kingdom, how can he tell if she is someone he would like to start a relationship with?
"I check her Bluetooth ID," he said. "If it's cute, then I'm pretty sure she will be pretty."