In Chapter 4, after doing the first chess puzzle, you will be chased into a hole by the giant unbeatable card monster. When you first arrive down there, go a short distance ahead and look at the right wall to find a heart stone. Shrink down to discover that it is a fake rock. Run into the keyhole tunnel and on the other side will be a floor where you can use a bomb to break. Do so, then go down the stairs to get a memory and extra teeth. Notice the skeleton sitting on the chair--it is Raz from Psychonauts. He can be identified by the red goggles, his shape, and the position that he is in (which is the stance he uses for a mind attack). It kind of looks like Raz is dead, perhaps signaling that there'll be no Psychonauts 2.