Easter eggs, by definition, are secrets or jokes you can find in games. Everybody Edits is no exception, and contains its fair share of easter eggs. A wide variety of said easter eggs include secret Smileys and website secrets.
Current Easter Eggs
In the game's files, someone found a sound titled "Over9000." Of course, when playing it, it would play an audio clip of the popular meme with the same name.
For a time, players didn't know if it was possible to play it ingame. Later on, someone discovered it was triggered after dying 9000 times.
Seems to be a mirror of the Beta site. Presumably used for testing exported updates.
Former Easter Eggs
During a short time, you could access a joke page that only said following:
Hai, sorry no porn here :(
The Rickroll easter egg was a secret world with the ID of PWr1ckr01lEI that had a Rickroll loop instead of a regular client. However, copying the ID into the "Join room by ID" button sends you to a world called "NVD Style" with over 12 million plays. As of 2017, the link on its own has broken, and you can only join by ID.
This mirror for the Rickroll site was put up shortly after user JaWapa was demodded. It was taken down due to mocking said user.
The Slime smiley is a secret smiley that was originally made by Cola1 and shown on the forums. It could be obtained from touching a certain decoration. It was added in the Halloween 2017 update, removed in the December 2017 update, and moved to the classic section on 12/03/17.