I created an "Extra Carbs" custom item in Fitday for when I'm too lazy to add in the 2 bites of DH's cake I ate, or those 3 french fries I stole from my sister at lunch LOL.

I just put in 4 calories and 1 g carb and everything else is 0, then I update the servings to the number of carbs I'm guesstimating.