Disclaimer: All characters belong to Uncle Rick. I am just borrowing. Pics and gifs from google.

Percy's birthday was always celebrated by a blue cake. There was one time Sally had told them about, when she had bought a chocolate cake which was black and Percy had refused to cut it. This year too they had prepared his special blue cake. The Stoll brothers however exchanged it with a fruit cake which wasn't blue and presented it. What shocked everyone was Percy happily cut it and celebrated his birthday. Little did they know that Hazel had manipulated the mist so that it seemed like a blue cake to Percy.