Best avoided at all costs. Unfortunately, as this video shows, that's not always possible.
We must acknowledge that without the awesome invention of dash-mounted cameras these videos wouldn’t be possible. It is also important to note that while the vast majority of these crashes emanate from Russia/Eastern Bloc, it is not exclusively the case. Make sure to watch this video of cars fishtailing and sliding all over the road with the sound up. The Australian commentary during one of the crashes is first class, the driver saying exactly what most viewers will be thinking.
While you watch from the comfort of your armchair (or toilet), remember there are idiots on the road. So make sure to always drive safely.