Several appeared at various rooms during the Halloween Party 2013. The internal names of these were "pumpkindude". Like this item, players could trick-or-treat at them.
Three appeared at the Snow Forts during the Halloween Party 2014, likely as an accidental leftover from the previous year. They served no purpose.
Trivia
For the duration of the Halloween Party 2013, interacting with this furniture allowed the Pumpkin Game to be played. However, like other pumpkins at the party, it needed a few minutes of time to "recharge" before it could be used again.
Until it returned in the October 2015 Furniture & Igloo Catalog, only one unit of this furniture could be owned.