Okay, It's from the game Portal, hosted on steam, developed by Valve. You have to go through this obstical course, and throughout the game, GLaDOS (the robot lady thing that leads you through the game) says things such as "quit now and there will be cake" and "when you're done there will be cake". When you're done and she tries to kill you (you escape) on the walls it's written like so:
The Cake is a lie
The Cake is a lie
The Cake is a lie
The Cake is a lie
:D
now, OH forget SUPER BOWL