... You are visiting your parents' house.

Let's face it, food from your hometown is the best food around, and you need to make sure you eat as many different kinds of comfort food as possible during your all-too-short weekend at home. Lucky for you, you leave the calories at your parents' place when you head back home!
To clarify, the calories DO count while you are at home, so don't stay too long or they will stick. But calories consumed in hometowns are officially designated 'Hometown Calories', and are not transferable to your new place of residence.