I enjoy a good, civilized debate now and then so let me continue by stating:
Writing "useless applications" is far different and less invasive than shocking someome as a practical joke. It's not practical if the victim should happen to be wearing a pacemaker or has other sinus rhythm problems or is triggered into a seizure. Chances are low that this would occur, but why take the chance? IMHO such mischievous circuits on one hand can be educational research. However puttting them into devious use is something else; just as nuclear technology used for peaceful purposes vs. mass destruction.
My high school electronics teacher used a charged 150v electrolytic capacitor to shock a student on the back of the neck, as a joke. The student fell to the floor, hitting his head, thereby sending him into some sort of epileptic fit. The student was rushed to the hospital and eventually recovered. The teacher was fired and now teaches at a small, private electronics institute getting paid much less and without the benefits the large school district provided. I remember him shocking students from time to time and after several years of it, his luck finally ran out!