Eggboy is one Of Muna and Daniel's Chicks, he used to be an Egg, but he hatched. Muna has a photo of Egg Eggboy and Daniel reunited after a huge battle. Now he is a small, cute, chick who always wears clipped diapers. He has taken a liking to Hamm, and often sneaks over to meet him. In Angry Birds Toons, He doesn't wear diapers that often.
In the LEGO series, Eggboy is called Eddy, and is not a baby, but instead aged 6, and a regular-looking Red-Jacket. Due to Rovio having bought off part of the rights to the Stories theme, it is unknown why he is called Eggboy, but probably to make him more Bird-like.