First, make sure you've unlocked the birthday cake from the store and have enough stars to purchase it. Purchase a new hamster of any breed/type and place it in the cage of your choice. Then, go to the "Special Items" menu, select the birthday cake, and place it somewhere in the cage away from the hamster. After placing the cake in the cage, you will automatically get over 1,000 stars at once. Remove the cake before the hamster begins to eat it and repeat the process to receive more stars. Repeat this as many times as desired to reach the maximum allowed stars in the game. Note: This glitch only works if the day you buy your new hamster is actually the hamster's birthday seeing as the birthday cake gives quadruple the stars on a hamster's birthday. This trick also works if your hamster baby is born the same day.