The cake is a lie

"The cake is a lie" is a catchphrase from the 2007 video game Portal. Initially left behind as graffiti by Doug Rattman to warn that GLaDOS, the game's main villain, was deceiving the player, it was intended to be a minor reference and esoteric joke by the game's development team that implied the player would never receive their promised reward. It became unexpectedly popular among Portal players, and has since become a widely distributed Internet meme where the phrase is co-opted and becomes associated with new meanings outside of the original context of the game.