Shocking children—in all ways—is very enjoyable for a physics teacher. I love the days that I can surprise them and nothing surprises them more than small electrical shocks. I have at least one day set aside in my Electrostatics unit for fun with my Van de Graaff machine using a structured question, prediction, test format. I start with making my hair and a few chosen students' hair stand on end while standing on the insulating stool. I move through a few demonstrations (full write-up available here) and ask students to apply what they know to each new scenario. We always have time for some fun afterwards which usually leads to some students shocking others.
This year I had a particularly enthusiastic group that wanted to take pictures and even came in at brunch to play, ahem, experiment, with the Van de Graaff machine some more.
Students were allowed to make contact with others either by "ET Touch" (touching outstretched pointer fingers), holding hands or fist bumping each other. We soon discovered that fist bumping each other was actually more painful that an "ET Touch." We tried to be as judicious as we could using the same two students and allowing one to "charge up" for the same amount of time. Both students involved said that the fist bump was more painful than the "ET Touch," and multiple pairs of students in different classes agreed.
The sparks we created were much more visually impressive when fist bumping than any other contact.
There's probably a reason for that...