Easter egg in Deus Ex: Invisible War's last mission - New York, Liberty Island. To get this ending, you must carry the flag on the left when you encounter the first ruined wall after entering the UNATCO base all the way to Manderley's office and throw it anywhere on the toilet - then flush the toilet. You'll be then be teleported to this room (Club VOX) where you can find the game's characters dancing along with Quote Files as a "blooper" section from the devs during the development of the game.
![](https://i.ytimg.com/vi/TozSf50GXq8/maxresdefault.jpg)