I was just reading in the news about how kids in the UK have subverted the "Mosquito" for their own use. For those of you out there who don't know, the Mosquito is a device that broadcasts a loud, pulsing 18-20khz tone. Many adults can't hear in this range, and the idea is to annoy gangs of teenagers who would ordinarily be "hanging out" in the area. So the teens recorded this tone, and used it as a ringtone for their phones, to be used in class. Most teachers are too old to be able to hear the tone, so it works perfectly. They call the tone "Teen Buzz" for obvious reasons.

The news report had a recording of one of these Mosquito devices, so I cut out the noise and enhanced the high ranges and this is my own version of it. It runs about two seconds.

Teen Buzz Ringtone (WAV, 255k)

If you can't open RAR files, get WinRAR.