Now through December 28th you can get Half Price Shakes from 2 pm-5 pm at Jack in the Box. I called a location in Idaho and they told me that they are participating.Ā  But I would double check at your location before you head out.Ā  Money Saving Mom is reporting that the Jackā€™s in Salt Lake City, St George and AlbuquerqueĀ  are not participating.