Apple recently recalled their AC plug adapters in several countries due to risks of electrical shock.
The two-pronged plugs were shipped to Continental Europe, Australia, New Zealand, Korea, Argentina, and Brazil, and are liable to break and shock you if you touch them. Not only were these adapters sent to a wide variety of countries, the time frame of the shipment has occurred in a huge gap as well. From 2003 to 2015, these adapters were shipped with Macs and various iOS devices (Apple). That includes the Apple World Travel Adapter Kit, which was sold in the US and the UK.
If you’re worried, look for a four or five character code on the inside slot of the adapter. If you see one of those instead of a three-letter region code, click here to exchange the potentially zappy parts for free.