Maybe not totally free, but BOGO (Buy One - Get One). From now today until December 16th, when you buy one holiday drink at Starbucks, you can get a second one for free! Get a Caramel Brulee' Latte, a Gingerbread Latte or Peppermint Mocha!
Just keep in mind the hours are limited, so visit between 2:00 and 5:00. Even if you're by yourself, wouldn't it be fun to buy one and give the free one to the guy pushing the carts in the parking lot outside, or drop it off after school hours when your child's teacher is most likely sitting there grading papers?
Find someone new to give it to for the next four days - it gives you some Christmas cheer without costing a dime extra!