If you're a big fan of Angry Birds and have always wondered on why these birds are always angry, then you have to watch these funny official trailer.

This video will show that Red (Jason Sudeikis) and his bird friends were once a very peaceful and lovely community. However, the main protagonist was an outcast in their place because of his temper problems and his super thick eyebrows. All was well until the mysterious green piggies who visited their island stole their precious eggs from them. Because of this, Red had to motivate his fellow birds by saying that "they are not supposed to be nice," thus our favorite Angry Birds were born.

Even though they are always angry, they are still cute, especially the little pink bird.

You can catch more of Red and his friends on May 13 in 3D!