economics question?

[Princess_LOLA]

You go out to a restaurant and order a lobster dinner for $40. After eating half of the lobster, you realize that you are full. Your date wants you to finish your dinner because you can't take it home and because "you've already paid for it." What should you do?
this is an actual microeconomics question, regarding the chapter on competitive markets and sunk cost, not a matter of a guilty conscience lol

[Lorenzo Ferlinghetti]

Eat as much as you can, and maybe ask your date to help you with it. If not, then leave it. What else can you do? We constantly waste food so don't feel all that bad about it. But if your conscience is troubling you, go do some volunteer work, donate supplies or money to some homeless shelter or to some third world country.

[beta_hat]

Assume that the benefit of eating is the direct utility you get from eating (the marginal utility is how much you get per mouthful as the mouthful approaches zero). The cost is what you pay for your food.
Having already paid for (sunk costs) the marginal cost of consuming an additional marginal bite of lobster is 0. As long as the marginal benefit is positive you should eat more. My concern, however, is that being full eating more lobster will make you sick and it will actually decrease your utility. This is a little tricky as a question because we usually assume at least weak monotonicity (more is always better than less) but if you reach a "bliss point" with respect to lobster consumption, eating more could in fact decrease your utility. I would interpret this as a negative marginal benefit, but the other way to look at it is that another bite of lobster give you:
marginal benefit - lobster is still tasty
marginal cost - you don't have to pay for more, but you will feel bad later, gain extra weight, etc.

so do marginal benefits outweight the costs?

[jacob.oost]

Eat until you are full. If you can't take it home, complain to the waiter about their lack of takeout boxes. Eating beyond the point of fullness would not be a gain for you. Let this example serve you in future decisions should you ever come to this restaurant again (or any restaurant with a stupid no-take-home policy).