I don't know if this works still. But the old school 1980's style arcade games 'could' be clicked and give you a credit.
If you get one of those hand held gas stove lighters, that use a little battery spark at the tip to ignite . . . well that little battery spark was enough to send an electric pulse down the wire and register as a credit. Hold it against the metal of the coin door and click the igniter, hence their name 'a clicker'.
It depends ( depended ) on if the coin door was earthed properly or not . . . not sure on the true mechanics behind it. More modern computerized coin counters ( the ones that can accept different coin denominations and tell the difference between a 5 cent or 10 cent coin ) , it wont work
Shit with some of the old one's, just a hard thump could bounce the wire that the microswitch used to 'count' a coin, cause that to bounce enough to register a credit. But that sort of thumping the machine would quickly get attention.
Oh and also here's one i know fully about, if the coin microswitch was wired incorrectly, it is permanently set to the ON position but it appears to work normally, it doesn't constanly rack up credits, it just holds at the current status, but then a coin passing through the mechanism, the coin briefly cuts the on signal, the machine then registers that as a single credit so as I said appears to function normally. BUT these machines would rack up a single credit when turned off and back on quickly. So you could turn it off, it would start up as normal ( pretty quickly too as the game does not need to load from a drive ) and then have a single credit waiting there.
#waistedyouth