My high school auto mech teacher from the 70s Did a demo with the class one time. He had a machine that showed how a HEI system worked. This was about the time that points plugs and condensers were no longer being put in cars. He had the class line up and hold hands. He took a spark plug wire and was holding it in one hand and with his Other hand held a students hand. All 8 of us students were n a line holding hands. When he turned on that machine instantly the kid at the end of the line start screaming and trying to pull loose. As soon as he pulled loose the next kid at the end got to pulling loose. And so on and so on till the demonstration was over.
Lesson learned. Don't mess with those spark plug wires while the engine is running.
