In chapter 4, click the wallet on the largest diploma behind Dr. Harburg's desk. A box, asking "Who are you?", will appear. Type: batman. If you do, the Egg will work and you'll hear an evil, deep voiced laugh. If you type anything else, Trevor's voice will say "Nope". Continue and watch the movie where Curtis storms out of Harburg's office. The doctor will eventually say "Next?" and "Batman" (actually Matt Jensen, Director of Photography) will walk into the room. Harburg smiles at this sight and laughter may be heard in the background. This gives 40 Easter Egg points.