After you complete all the levels of Angry Birds Seasons Summer Pignic (don’t have to 3 star them all) there is the surprise video you can see if you happen to tap the picnic basket icon on the completion...
We found the hidden Golden Egg that opens the secret Super Bowl level! Find out how!
Check this out! During the Super Bowl the Rio commercial will contain a "secret code directing Angry Birds players to a special level in the popular mobile game". I betcha I know which level.
The “Special Present” on the far left of the screenshot below became available on December 25th. Tapping it loads the video below the image.