Bluetooth enables devices within a few meters of each other to exchange information wirelessly--a technology that users with Bluetooth-enabled mobiles are making the most of to send text messages to strangers anonymously.
This drive-by messaging has been dubbed 'bluejacking.'
But why would somebody bluejack a stranger's phone? The motive behind the craze is to freak out other Bluetooth users that you might encounter in public--for example, a bluejacker will check out other Bluetooth users on the tube and drop them a message that only someone in the same place will appreciate, for example, their choice of newspaper or color of their top or just a message to let them know that they've been bluejacked.
How do you bluejack? By saving a message in the 'name' field of your phone, for example, "Nice tweed trousers", then choose to send it via Bluetooth--a list of enabled hardware in the vicinity should appear on your phone, select the device you want and off you go.