The best way to promote your brands during the holidays is to start a contest and offer your products as prizes to be won. With traffic increasing drastically in december on facebook, it is ofcourse the best place to hold these contests.
It has also been found that contests submission increase by 66% during the holidays and a 47% increase in custom Facebook Page app views as well.
So if you are thinking of running a contest to promote your brand at the last minute, you might want to try a few well-used ideas like contests about photo sharing where you ask the consumers to share pictures of them in their holday costumes, or their best family picture or even the most awkward family picture etc.