Quoted from mg81:I would disagree with this statement. The neutral prong of an outlet will also work just fine as a "ground". The neutral and ground wire are connected at the main service panel, so either wire will make a fine "ground" for a built up static charge.
If I was making a bet I would guess that the OP's pin either has the grounding prong cut off of the plug (commonly seen) or that his outlet is not correctly wired and does not actually have a ground (common depending on where he lives. In my part of the country we are full of homes that were built before grounded outlets were used, so it is common to see homes "upgraded" by installing a 3-prong outlet but not actually ground the new outlet.)
Incorrect-ish. Nuetral does go back to ground but in pinball machines the neutral prong wont provide a path to ground from anything grounded to the braid in the machine unless there is a bond between ground-braid and line neutral in the actual pinball machine which testing a few games of mine the lockbars have continuity to ground prongs and not line neutral therefore line neutral doesn't provide a ground path for any "ground" in the game therefore static can still build up without a proper ground. Code stipulates one bond between neutral and ground and yes its at the main service panel. my guess is his game had static build up from his ground braid probably from not being a true ground and electrons jumped from the machine to him, not the other way around. take a meter and ohm between your lock bar to a ground prong on your plug to your pinball. after that the outlet tester as terryb suggested is the best way to see if you actually have grounded outlets back to the panel. grounds are super important, my black hole was shocking me very lightly until i fixed the plug and put a ground on it.