“A lot of girls do it,” said an 18-year-old named Sara al-Tukhaifi who explained that a girl and her friends might cross-dress, sneaking thobes out of a brother’s closet, then challenge each other to enter the Saudi male sphere in various ways, by walking nonchalantly up to the men-only counter in a McDonalds, say, or even by driving.

“It’s just a game,” Ms. Tukhaifi said, although detention by the religious police is always a possibility. “I haven’t done it myself, but those two are really good at it. They went into a store and pretended to be looking at another girl  they even got her to turn her face away.”

Grinning, Ms. Tukhaifi mimicked the gesture, pressing her face into the corner of her hijab with exaggerated pretend modesty while her classmate Shaden giggled. Saudi newspapers often lament the rise of rebellious behavior among young Saudis. There are reports of a recent spate of ugly confrontations between youths and the religious police, and of a supposed increase in same-sex love affairs among young people frustrated at the strict division between the genders.

And certainly, practices like “numbering”  where a group of young men in a car chase another car they believe to contain young women, and try to give the women their phone number via Bluetooth, or by holding a written number up to the window  have become a very visible part of Saudi urban life.

Flirting by Phone

A woman can’t switch her phone’s Bluetooth feature on in a public place without receiving a barrage of the love poems and photos of flowers and small children which many Saudi men keep stored on their phones for purposes of flirtation. And last year, Al Arabiya television reported that some young Saudis have started buying special “electronic belts,” which use Bluetooth technology to discreetly beam the wearer’s cellphone number and e-mail address at passing members of the opposite sex.

Image Shaden, 17, at her home in Riyadh. She spoke admiringly of the religious police, whom she sees as the guardians of perfectly normal Saudi social values, and she boasted about an older brother who has become more strict in his faith. Credit... Photographs by Shawn Baldwin for The New York Times

Ms. Tukhaifi and Shaden know of girls in their college who have passionate friendships, possibly even love affairs, with other girls but they say that this, like the cross-dressing, is just a “game” born of frustration, something that will inevitably end when the girls in question become engaged. And they and their friends say that they find the experience of being chased by boys in cars to be frightening, and insist that they do not know any girl who has actually spoken to a boy who contacted her via Bluetooth.