Such a popular trick!
Many routines have been written for the Egg Bag, because there is so much you can do with it.
The basic routine goes like this: place an egg into the bag. Turn the bag inside out- the egg is gone! Let the spectator reach into the bag- the egg is back inside the bag!
Much more is possible! You can also use this with your own small ball, such as a sponge ball or ordinary rubber ball, instead of an egg.