Instructions
Tap the "Go Out" button; then tap "Walk." An image of your dog's neighborhood will appear in one screen, and an overhead map of the same area will appear in the other.
Drag the stylus across the screen in the direction you want your dog to move. Explore the neighborhood, using the overhead map to seek out question-mark boxes. Open these boxes to retrieve the presents inside, and keep an eye out for unboxed presents lying around the neighborhood but not indicated on the overhead map.
Continue opening boxes and picking up presents until you find a piggy bank -- the presents that appear are randomized. Once you have the bank, you can either sell it or break it open for a random amount of money that may be less or significantly more than the amount obtainable through sale.