I have no idea what these references mean, and neither will you if you have not played Portal. But Cam was chuckling to himself in a knowing way at all stages of his cake-making, and had very precise ideas about the cake's shape, colour and message. So I presume if you were a teenage boy you'd get it.
And here it is in all its geeky glory - The Grand Portal Reveal Cake:
|"The cake is a lie"|
|Orange and blue marbled sponge inside|