Locked Worlds
You can access the locked worlds of "Angry Birds" without completing every level. From the main screen of the game, move any locked world that you want to access into the screen center. Press the back or home button on your device. This will remove you from the "Angry Birds" app and return you to your device's home screen. Touch the "Angry Birds" app icon to load the game again. Wait for the "Play" icon to appear, and then tap it repeatedly and quickly as soon as it appears. The previously locked world that you had centered on-screen prior to exiting the "Angry Birds" app is now unlocked, and the Stage Select screen will appear for that world. At this point, you're able to select stage one and must pass through that stage to go on to the rest of the locked world. Repeat this process for any locked worlds that you wish to access.
Red Bird Noise
Any time you're able to use the big brother red bird or the standard red bird, activate the slingshot. Pull the slingshot back and launch the bird. Once the bird is airborne, tap the device's touch screen to make the bird make a funny sound.
Simplified Green Bird
To use the green bird more simply, launch it firmly in a backward direction, rather than launching it in the standard way, and then tap the screen immediately so it turns around and goes straight at the pigs. The green bird is also called the Boomerang Bird, and launching it normally and then tapping the screen causes it to boomerang backward. Launching it backward avoids the boomerang effect, which is helpful if y need a straight shot.
Extra Yellow Bird Damage
The yellow bird is the fastest of the birds, and once you launch it you can do very fast screen taps to make it go even faster. You can inflict extra damage on the in-game structures, and thereby kill more pigs and rack up more points, by aiming the yellow bird at the wooden structures since they'll break the easiest. The yellow bird's speed will cause extra damage to the wood, shattering it.
Unlock Sound Board
Play through each of the first three levels in "Angry Birds," earning three stars on each level, to successfully to unlock the sound board for the game. The sound board option will appear in the Bonus section of the menu screen.