I used to pull this scam a lot but it is very difficult to do as you need someone working n the store to help you. Basically, whenever an item goes on sale, say a video game is 15% off, your friend at the store prints you a receipt saying the item on sale was not in stock. Take that to a different store, and atleast with target, on the bottom it says exchangeable for any other similar item. So, now you can get whatever game you want for a 15% discount.

Sorry if that didn't make sense.