Originates from the the 1975 movie "The Rocky Horror Picture Show," when the cast had an Easter Egg hunt but most of the eggs went unfound. They can be seen throughout the film in various locations (such as under Frank N. Furter's throne).
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.
2) Wow, Strong Bad's emails are not only funny, but the Easter eggs really make me pay attention.