The most popular Easter egg in Grand Theft Auto San Andreas seems to be making the moon balloon up. To do this, you need to get a sniper rifle at night and then position yourself so that the moon is in the center of the scope. Each time you shoot it it will get a little bigger until it reaches its maximum size, which will then send it back to its original position after the next shot. While this isn't a major cheat for Grand Theft Auto San Andreas, it's more for fun and to show your friends that you can do something they can't - shoot the moon!