Oh Grechen Rubin - you've got me on this one. Big time!
One of my absolute favorite things to do is give myself license to do whatever I want after doing something good. If I don't spend any money for a few days, I let myself buy a pair of shoes. If I eat well, I take this as permission to eat all the donuts in the world.
As she explains here, this is a behavior that you should be weary of. The Licensing Effect can hamper your weight loss efforts, blow your budget and just plain old get you in trouble. Beware!