Like a few other traditions, Easter has its followers and they're well represented by children whose innate desire to seek and find things is matched by the chocolate goodies hidden for their pleasure.
But Easter Eggs take on a different meaning when it comes to software applications. They're fun little surprises tucked away in undocumented code and waiting for someone to trigger their launch sequence. For instance, the Google rotation roll that ensues once you type in "do a barrel roll" or any number of other hidden tricks.
Although these neat things can be hidden in anything from paitings to cars, you should always try to avoid Easter Eggs in systems and software intended for work. Why? Because by being undocumented, they increase the likelihood that they might represent a weakness in the software. They can do this in a variety of ways, from crashing the application if they don't see the input they expect to allowing malware to disrupt the system if no adequate protection is in place.
So if you're in charge of purchasing software, or sourcing technology, looking for undocumented 'features' should be a part of your selection process as a security measure against inadvertent vulnerabilities. But if you're like most people and are looking to enjoy Easter with your family, carry on, and don't worry about work until next week.