Often I hear the joke about old people tellking kids to stay off their lawn. If this thing gets popular, teenagers are going to have to closely mind their proximity to senior citizens cars, homes, and walking routes. I can imagine multiple houses in each neighborhood with these doggy teenager whistles screaching constantly at anyone under 20.
"Shopkeepers in central England have been trying out a new device that emits an uncomfortable high-pitched noise designed to disperse young loiterers outside their stores without bothering adults. The noise can normally only be heard by those between 12 and 22 and it makes the listener feel uncomfortable. Once in their early 20s, people lose their capacity to hear sounds at such a high pitch."