This decorative item was the day 16-19 gift from Advent Calendar 2009. If you logged on to Island Paradise that day, you should find one in your inventory. Some players got a lucky glitch and ended up with more than one Snowman. If you had logged in on that day but did not receive your Snowman, contact support.
It was re-released for Advent Calendar 2010. It cost 5000 c to buy and gave 50 xp when purchased. The description read "Watch out for the midday sun, Frosty!". It was re-released for Advent 2011 from December 10-24, 2011.