The phrase the cake is a lie had it's origins on one of the *chans. It started in the lolicon image board also called "/cake/" or "Delicious Cake" (Lolicon being drawn pornography depicting small children doing sexual favors.) On certain chans (Which will go unnamed) the /cake/ board shows picture of real small children instead of drawn. similar to their /jb/ or jailbait boards. Some of these picture can be found with a tag on them saying "Open with winrar". When you do this these certain picture open text documents with links or bat info that leads to child porn or "CP". when people would open these in winrar most of the time they would be linked to such a website as Goatse or tubgirl. The receiver of "CP" would then return to the original thread and tag it with the phrase "The cake is a lie" cake being Child Porn. This phrase is often mistaken for portal where at the end you are rewarded with cake promised throughout the game only to have it taken away. But that would leave incorrect. The meaning of this phrase was lost some time ago and was only brought back when portal was introduced and it fit so well.