I'm sure that everyone is on the right track. Right now I don't seem to be able gather up enough brain cells to see where the problem might be; but when I was a small lad I found out quite by accident what causes the shock. I had a bicycle with a horn. Since I took everything apart, I took the horn out. While holding the wires for the horn I touched then to the two "D" cells that usually powered the horn. As long as the horn was sounding - no shock. As soon as one of the leads came off you got quite a shock.
I found out about collapsing fields and how their voltage is much higher than the source voltage. I wonder if you get a shock while the horn blows or after? John