i was electrocuted by a souped up tens unit, same idea as a zapper (but higher voltage) - an unusual response for sure - but it did happen, and i have been disabled since, have never worked another day. if you're curious about the specifics, check the pet forum, there's a lengthy discussion there.
yes i am aware that most people suffer no ill effects from zapping - so please everybody don't respond to my note saying that i am nuts, or wrong. this is my experience, and my experience only.
still, i feel i must say what my experience, so that others can consider it. to do otherwise would be unconsciencable