With their incessant texting, hip-hop ring tones, and superior technological skills, it's pretty easy for teenagers to annoy you with their cell phones. Well now you can annoy them right back, with an iPhone app appropriately named "Annoy-a-Teen."
It turns out that, just around the time that people lose the inclination to roll their eyes when asked to take out the garbage, they also stop being able to hear tones at frequencies above 16 kHz or so. Using the Annoy-a-Teen app, you can set your phone to emit a tone that is silent to you, but supremely irritating to them. Commenters on the download page at Apple are complaining that the app no longer works, but they're probably just getting old.
