Perform the followings steps to unlock all worlds without playing through the game.

1. Load up Angry Birds and go to the world select screen.
2. Center a locked world on the screen.
3. Push back button all the way out of Angry Birds.
4. Load Angry Birds back up and when the "Play" button appears tap it rapidly.
5. You should be inside the locked worlds stage select screen.
6. Now, pass the first level of each world to unlock it.