Have you ever been doorbell ditching before? The point of the prank is simple: Sneak up to someone's front door, knock loudly or ring the doorbell, and, instead of greeting whoever answers the door, run away and hide somewhere nearby. The joy of doorbell ditching is, of course, reveling in the homeowner's confusion and rolling with laughter under the security of his nicely trimmed bushes. Although the game might get you in a bit of trouble if you happen to incite the ire of a cranky neighbor, it's mostly a harmless joke on par with a prank phone call.

For more technically inclined pranksters with access to Bluetooth technology, however, there's the digital version of doorbell ditching and prank phone calls: Bluejacking. A kind of practical joke played out between Bluetooth-enabled devices, bluejacking takes advantage of a loophole in the technology's messaging options that allows a user to send unsolicited messages to other nearby Bluetooth owners.

The only difference between doorbell ditching and bluejacking is that bluejacking usually isn't done on your neighbor's lawn. Instead, a bluejacker will most likely camp out in crowded areas like shopping malls, airports and subway systems to find victims -- places with a potentially high percentage of people with Bluetooth-enabled devices. The trend has even fostered fan Web sites, where Bluetooth users inform newcomers how to bluejack, trade tips and post amusing bluejacking stories that include every keystroke and puzzled look.

­So how is bluejacking done? What is it about Bluetooth technology that makes it possible to bluejack? Does it have anything to do with hijacking information from another Bluetooth device, and can it cause any harm? Are there any privacy concerns? To learn how bluejackers engage each other, confuse one another or simply annoy innocent bystanders, read the next page.