Intended to allow switching electrical power to two low-wattage devices on and off with hand claps (two for one device, three for the other), it was in fact sensitive to any sharp noise, so you could find your light turning on and off from gunfire on television programs, and the fun that could ensue once your dog learned to operate it by barking was endlessly amusing.
It had only stupid U.S. ungrounded power outlets for loads connected to it, which was probably a good thing because having high wattage devices such as space heaters and air conditioners switched by random noises isn’t a particularly good idea. Note that the patent shows such a device connected to a television set, which creates the possibility of the TV randomly turning itself on when the Clapper hears loud noises that trigger it, then back off when the TV sound triggers it again.
On the other hand, it doesn’t listen to your conversations at home and report them back to a corporate oligarch and the panopticon state.
You can still buy one at Amazon.
Me: “Alexa, order a Clapper to activate my automated gun turret.”
Alexa: “Are you sure you wouldn’t like me to control that for you?”