Go to level 21 or 24 of Utopia and fire it anywhere. Once it hits something, it will sound like an exploding Bomb Bird. This can also happen in level 12 of Pig Dipper too. Same with level 5.
On the last level of Utopia, shoot the Ice Bird by the Fat Pig while he's chewing so he won't eat the Ice Bird and let him explode on his own. At first, it will sound like the Fire Bomb Bird, but if you try again, he will not make any noise.
At level 8-30. When you send Ice Bird towards one of the asteroids, he won't freeze the asteroid!
Go to any level (best if you do 4-11) and pause when you do anything destructive. You'll see some points go away a second later.