If you eat something, but no one else sees you eat it, it has no calories. When drinking a diet soda while eating a candy bar, the calories in the candy bar are cancelled by the diet soda. When you eat with someone else, calories don't count as long as you don't eat more than they do.
Foods used for medicinal purposes never count.
If you fatten up everyone else around you, then you look thinner. Movie-related foods do not have calories because they are part of the entertainment package and not part of one's personal fuel. Cookie pieces contain no calories. The process of breaking the cookie causes calorie leakage. Late-night snacks have no calories.