Simpsons, The Easter Egg - Not Sid Was Here Egg

First go to coaglation, doesn't matter what options just do anything. When you spawn go to the tunnel with the water the has either a shield boxy thingy or an invisibilty thing. Go to the upper level where you can see the water through a giant hole in the rock wall. Look to your left and look at the side of the the rock wall to see a message that says "Not Sid Was Here."