October 31 may be one of those days. Those days where it's almost impossible to cheat on your diet. If you're on a strict diet I'm sorry for tempting you, keep doing what your doing. But if you're NOT in "strict" diet mode here is a strategy for eating bad while minimizing the effects of fat gain.
You need to empty your sugar tank. Here's how it works: 3 days prior to the "distraction day" make sure to consume little to no carbohydrates in your diet for 3 days straight. Make sure to exercise hard with high repetitions (15-25) to use a lot of glycogen. Then when the day comes for you to consume carbohydrates, most of it will be stored as glycogen and you won't have to worry about it spilling over and making you fat.
Note of caution: Don't do this too often or you will still get fat.