Easter egg

An easter egg is a small item, usually an inside joke, hidden in a program which is accessed by performing a certain sequence of commands. The first easter egg was found in the Atari 2600 video game Adventure. By finding a rare item and heading to a specific location in the game, the character could pass through a wall into a hidden room that contained the programmer's initials. Easter eggs are present in most computer programs, video games, and DVDs.