In the episode where the growns ups are fighting over anti-war and pro-war, the boys are all sitting in a study group in the house. The parents come up to them and ask them join join their peace concert. One of the boys says " We can't, were studying for this test Mr. Garrison gave us.'" Right about this time, if you look in the small group of adults, you can see Mr. Garrisons faceless head in the very back, and as the scene continues, he keep moving deeper into the group.