Samoa sits on the International Date Line and is currently on the Western side of it, sitting about 5 or 6 hours behind America. It was set up this way 119 years ago because its main export markets were with the USA.
However, their main markets nowadays are in Australia and New Zealand, but they are currently 20 or so hours behind.
To rectify this after Dec 29th, Samoa will miss a day out and go straight to Dec 31st and go three hours ahead of Australila and New Zealand instead. With the added bonus of getting to be one of the first places to see the first sunrise of the year.
More on their time travel exploits here.