The current passed from a buried device through the stream, then through the employee's body and out through his shoes? If there happened to be a grounded pipe nearby and the employee happened to beholding onto it while relieving himself that might work.
Have you read Olson's story of being shocked while standing partway up a ladder when it mysteriously jumped into an open electrical cabinet mounted to the surface of a beam near the ceiling of some warehouse? That one also presented some interesting challenges to laws of physics.
The unbelievable part (for anyone who knows the first thing about electricity) was how he managed to get shocked while standing partway up the ladder. Have you ever seen a bird on a high tension wire? Notice how they don't get shocked, even though the cable may be carrying 50,000 Volts?
But I digress. In the present story the conductor is already making ground contact. The victim, unless he's otherwise grounded) offers far greater resistance to earth than the plate sitting on the ground. A worker wearing typical workboots can touch a live conductor and feel nothing... unless he touches ground at the same time. If you touch the output of a spark coil while leaning against the fender of a vehicle, the current will flow through you, jump the gap through your trousers and give you something to remember. But in this case the current would pass harmlessly from the plate into the ground if the other end of the coil was also earth grounded. If not, it wouldn't go anywhere.
In all probability the guy who told you the story made it up. It sounds funny at first but I doubt he actually did it.