The most useless machine in the world.

This machine exists only to switch itself off.  That's what I call a machine.

One of my readers offers this excellent idea:

"Many of those hyperactive kids need something that they want to beat and most ly do so, destroying whatever it is in the process. Now put one kid infront of this machine and ask him to try to beat the machine. My best bet is he will eventually give up and be so tired he will fall into bed.
Get two machines and two kids, offering them a competition to see who can beat the machines . If nothing else a lot of hilarity should ensue."

Great plan - I hope the machine is strong enough.