I don't see how a person could get shocked from that. Burned I could see.
First, I received the service call because an employee got shocked and experienced a boom at the same time. They discovered the penny when they saw the charring on the front of a power strip (in a commercial office) Looking at the depth of the grooves, I'd say the penny had been sitting there a while, arcing away without tripping either the strip or branch circuit breaker.
Apparently, he accidentally pressed the penny into firm contact with the prongs and, theoretically, received 60 volts to whatever grounded surface his other hand was on. He actually could have received any voltage between 120 and zero, but it was enough that he went home for the day (which is why I'm guessing hand to hand current pathway), but he was otherwise okay.
My long-term solution was to tidy up the rats' nest (clic pics for bigger rats); I hear management really liked it:
Before:
After: