The term “Easter egg” is usually used to refer to a hidden bonus in a movie, computer game, or electronic file, which rewards the finder either through the finding (“I found the hidden reference”) or as an extra music track or game level. The term nowadays is also applied retrospectively to such things as Alfred Hitchcock’s cameo appearances in his movies. The reward for the viewer is simply the fun of spotting Mr. Hitchcock in the background of some scene or other.
For magicians, an equivalent reward might be a full-deck stack that is published and used by lots of performers, but which has a number of poker-deal combinations hidden within the stack, which are not publicized and are only spotted by astute users.