When I was younger I used to love the 9v battery trick, lol!
At my old work one of the routine services that had to be carried out just happened to be a lawn mower, (I'm used to working on big earth moving machinery/trucks etc... So a lawn mower should be easy enough!) Needed to check the spark from it, plug the coil lead into a spark checker thingy they had, while holding the coil lead/connection yanked on the ripcord, gave me a nice tingle. Not to mention the numerous times checking dirt bike plugs out in the bush, to see if they're fowled or not.
And one little zap from 240v, was plastering around a power point/ceiling fan switch, it was loose so I lifted it up to get the scraper down beside it and touched the terminals on the back of the switch (with the hand I was holding the switch with, not the scraper)
So, c'mon, share your stories ari, we know you've got some!!