The cake is a lie is a metaphoric catchphrase that originates from the 2007 video sport Portal.
The idiom sends the message that the promise of a reward is merely a false motivator, and that there truly is no reward in the finish.
It’s like while you inform your child that if he behaves properly he’ll get ice cream later, however you haven’t any intent in any respect to truly give him ice cream. The ice cream is a lie.
The cake is simply a trick to lure you into doing one thing that most of the time will lead to disappointment, and possibly even downfall.