intentional inside joke, hidden message or image, or secret feature of a work
The secret room in Adventure with Warren Robinett's credit. Adventure is typically regarded as one of the first video games to feature an Easter egg.
An Easter egg is a message, image, or feature hidden in software, a video game, a film, or another—usually electronic—medium. The term used in this manner was coined around 1980 by Steve Wright, the then-Director of Software Development in the Atari Consumer Division, to describe a hidden message in the Atari video game Adventure, in reference to an Easter egg hunt.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).