1) A painted egg, often hidden by the Easter bunny on Easter. May also be a chocolate egg with some sort of filling.
2) A secret, hidden inside a video game, DVD movie, or even one of Strong Bad's e-mails. Often, it's not needed to progress a story.
1) 8-year-old: YAY! The Easter bunny rules! He brought me some Easter eggs.
2) Wow, Strong Bad's emails are not only funny, but the Easter eggs really make me pay attention.