Go to The Big Setup level 9-14. The golden egg #14 is wearing a safety helmet and placed on the right side of the level, reachable only with the boomerang bird.
Below you will find the video that shows both the location (or how to find it) and the starred golden egg level walkthrough itself. The golden egg level could take several tries until you star it with only the big brother.
Go Back To Our Angry Birds Golden Eggs Guide