A couple of funny things happen when the temperature gets down to minus 40° degrees. The first is that the Fahrenheit and Celsius temperature scales intersect. The second is that all your nose hairs instantly freeze solid.
The International Date Line isn’t a fixed line at all, but actually sort of follows the 180° longitude line, zigzagging its way through a bunch of small islands, territories and nations. More interestingly, it also allows you to semi-time travel.