LONDON – Commuters take note — the respectable person sitting next to you on the train fumbling with their cell phone might be a “toother” looking for sex with a stranger.

“Toothing” is a new craze where strangers on trains, buses, in bars and even supermarkets hook up for illicit meetings using messages sent via the latest in phone technology.

“Toothing is a form of anonymous sex with strangers — usually on some form of transport or enclosed area such as a conference or training seminar,” says the “Beginner’s Guide To Toothing” on a Web site dedicated to the pursuit.

It is made possible by Bluetooth technology which allows users to send phone contacts, pictures and messages to other Bluetooth-enabled equipment over a range of about 10 metres (yards).

Users discovered they could send anonymous messages to people they didn’t know with Bluetooth equipment, spawning a craze dubbed “bluejacking”.

Jon, aka “Toothy Toothing” and the guide’s author, explained toothing was born after he was “bluejacked” by an unknown girl while commuting to work in London. After a few days of flirting, she suggested a brief encounter in a station lavatory.

“The meeting wasn’t a romantic thing — it was purely sexual. Barely anything was said,” he told Reuters via e-mail.

He said potential toothers begin by sending out a random greeting — usually “Toothing?”.

“If the other party is interested, messages are exchanged until a suitable location is agreed — usually a public toilet, although there are tales of more adventurous spots such as deserted carriages or staff areas,” his guide adds.

Jon, who’s in his 20s and works in finance, estimates there could be tens of thousands of toothers from all sorts of professions and lifestyles. Certainly the Web site’s message board is busy.

“Any toothing on these trains?” asks one poster about services between Cambridge and London, prompting positive responses from “Dannyboy” and “Zeke”.

“I’ll be around London Bridge mainline station around 9.45 – 10 a.m. tomorrow if anyone’s interested…,” another poster called “Boi” wrote hopefully.

While some happily recount their successful encounters, others suggest there are a few teething problems with toothing.

“I tried toothing in Tooting (south London) last night… not a device to be found,” a frustrated “Snowdog” posted sadly.

Although clearly not what the industry had in mind, toothing may lead operators towards similar, more mainstream projects.

Last month it was reported that a team in Boston had created a service for cell phones called Serendipity, a wireless alternative to online dating.

It allows subscribers to store their personal details and what they want from a partner and when there are enough similarities between two people and they happen to be in the same area, it tells their phones to communicate with each other.

Dario Betti, of the British-based consultancy Ovum, said bluejacking had really taken off, helped by the fact the service was free. “The element of the unknown, that you are connecting to someone around you that you might not know, it’s a novelty factor that is helping it to start,” he told Reuters.

If Jon and those who use his forum are right, toothing is certainly livening up life for some bored commuters.

“A lot of my day’s taken up with a soul-aching commute into the city, and that just feels like dead time,” Jon said.

“Flirting is fun, sex is fun. We’re just employing expensive, complex toys to find the most basic form of entertainment.”