The Mosquito is a device that helps you to keep all those damn loitering kids off your lawn by emitting sound at high (17.4 kHz) frequency, which only kids can hear. Its 8 kHz mode helps you to keep everyone off.
If you feel especially sadistic, there is a “MUSIC” version, which is somehow legal to use in public places (as the MST site states), and plays the music which nobody likes. With The Mosquito, you’ll become the worst nightmare of those loiters – “the high-frequency overlord”, as they would call you.
The best part is that it is not just annoying: as cited in Wikipedia, “with the sound levels that can be reached by the device, the onset of dizziness, headache, nausea and impairment is to be expected”.