Rocks or Nintendo?

When a florida teen opens his birthday present and finds a new nintendo ds he is very excited and why shouldnt he be. This excitement would soon be disappointment. After tearing off the plastic wraping and protective stuff he opened the box only to find Chinese newspaper and lots of rocks. What. How this happend or why i dont know. The mother who had bought the gift immediatly took the gift back to walmart and walmart told her she would have to contact nintendo. Eventually walmart gave her a full refund and a gift card. How can a huge store like walmart sell products filled with rocks?