You are picking up a bag of fast food, including two orders of french fries. On the drive home you do what comes naturally: you graze from the top of the bag, consuming fries until you get home.
When the time comes to dole out the meals and the fries, you are faced with a choice. Do you present the other party with the partially depleted portion of fries, hoping that they blame the deficiency on random chance or do you take the smaller serving?
Maybe you deserve the extra grazed/poached fries as compensation for picking up and hauling the food home? Or maybe you are actually stealing from your dining partner?
I think the best solution is to apply a french fry fairness doctrine. Spread the wealth around a bit. Combine the french fries into a shared pool and enjoy your meal.