Apparently, a young Chinese woman, just out of her bath, answered her iPhone while it was being charged and was electrocuted. The phone was being charged with the proper charger - original equipment. Made for Apple.
This cautionary tale should serve as a warning. Never handle electrical and/or electronic equipment connected to an electrical source while wet, or in or near water. If you're just out of the shower, don't handle or use your phone. If you're hot and sweaty from exercise or work, don't handle your phone.
Make sure the wires are not bare anywhere and that the ends are not exposed. Make sure the charging block is not cracked and the seams are closed.
Be dry. Be unplugged. Be safe.