! 
Such entertaining sarcastic wit
In answer to James L., I said “mistakenly“ not accidentally. I figure if you are receiving a shock downstream, it must be due to a mistake. I am speaking of feeding the line side of a GFCI receptacle with a 2 wire cable with no grounding conductor. Then “mistakenly” connecting the grounding wire in a 3 wire cable to the load side of the GFCI to feed outlets downstream. At this point, if you touched the yoke on a downstream receptacle, you received a shock. Eliminating this connection corrects the problem. I experienced this decades ago and am simply asking the question as to why this occurs. Is it due to induction from the internal CT’s or what? And yes, all the neutrals and hots were made up before and in a de energized condition.
In answer to Mr. Alwon’s question, I agree that you do not actually have an equipment ground in a 2 wire system. And I have already answered “yes“ to the question as to whether I am a retired electrician. I assume you may be implying that I must be incompetent for asking such a question. Perhaps it seems elementary to you but I venture to say other folks would like to see your answer, as well.
Such entertaining sarcastic wit
In answer to James L., I said “mistakenly“ not accidentally.
I mistakenly typed accidentally 
Sure, could be induction. EMF, ghost voltage, etc.
But if you grab a yoke and get shocked, you more than likely have some kind of fault.
It's entirely possible that the metal box with the 2-wire in it was actually grounded from behind, but cut off somewhere, and when you screw the device in it's got a long lead of wire running off somewhere.
I actually had that, where someone had added grounding to all the metal boxes in a house, and connected it to a water line in the kitchen. Someone else came across and hijacked that ground wire and use it as a neutral buy pigtailing off of a switch box that had only a switch loop. Someone else apparently came by and "fixed" the outlet the head lost its bootleg neutral, but left that bootleg neutral hooked up. There was real voltage on those boxes, and thefore the yokes.
! Well, I ran across a similar situation recently where a dishwasher circuit was fed off the load side of a GFCI receptacle. It was a 3 wire circuit on both sides of the outlet but the frame of the dishwasher was hot. Upon further checking, the equipment ground on the line side had a break in it and I assume this was the cause. Someone else suggested it might be static but I checked it with a wiggy.
Interestingly, yes. I suspect that the shock you experienced comes from the "grounded neutral transformer" circuit of the GFCI itself.
. Now I know why it is in there. But I knew I hadn’t imagined receiving a shock. Have a nice day, sir!I don’t see that in his avatar, but then I didn’t click on his profile either though.
Nope
