Ratchet and Clank 2 Easter Egg - Jak and Daxter Cameo

On the level where you have to rescue and re-active clank,do that, then do as the mission screen tells you and go to Clank's apartment. In there,if you look at one of the walls, there's a big drawing of Jak and daxter and a PS2 on the table beside it! The creators of Jak and Daxter, Naughty Dog, created a code which is used in the Ratchet and Clank games.