My guess is that right before you get to GlADoS (if thats right) you'll find a dead combine, take his AR2, go in, kill GlADoS, then you have to fight the combine with gordon freeman, in the end - you'll be teleported to combien planet wif teh special suit to kill advisors then it'll turn out that Portal 2 was actually HL3 or HL2:EP3 and then when you kill the final advisor you get teleported into time to the time where Apeture Science rules all and it's the combine takeover again but with Apeture Science and you have to fight the Combine Android Soldiers with Ellis, Rochelle, Coach, Zoey, Bill, Louis, Francis, Nick, then you will finally defeat them and find that the cake is NOT a lie, and it is not a pie, or a spy. You eat the cake.