I found this neat little glitch in Yoshi's Island DS that allows you to have a Giant Egg. This glitch requires Baby Mario, a Superstar, and a nearby Middle Ring. While the effect of the Superstar is in effect, run into the Middle Ring. Then, should you die, you'll respawn at the Middle Ring with a Giant Egg to go along with your other eggs. The Giant Egg is heavier than any other eggs, so it can't be thrown very far and doesn't bounce.