I lived in a tiny camper for several years.
At one campground I did not realize the polarity of the electrical outlet into which my power cable was plugged - was reversed.
This came to my attention one evening when entering while it was drizzling.
When reaching for the grab-bar by the entrance door, I received a mild shock.
Of course, I had to step back and repeat - yes it definitely was a shock.
It was remedied the following day!