Grounding wires. We could be like the Japanese. They still use 2 pin plugs in a lot of places. Most appliances are double insulated because of this, but needless to say, many aren't. They have what I think grounding wires are... Basically a 2 pin plug, with a wire that comes off with a clamp on the end. Clamp it to a water pipe, enjoy being electrocuted later thanks to good ole plastic pipes. That is (or at least was) the official system. In practice, I suspect they just have grounded plugs and sockets now.
Many sockets are unpolarized, and in the earlier days most appliances had the neutral tied to the case, since they were imported from USA. So hot chasis was a common occurence in Japan.