In a medium bowl, mix the graham cracker crumbs and oatmeal, set aside. Using a large saucepan, stir the sugar, cocoa, milk, and margarine over medium heat until dissolved.
Bring the mixture to a boil and let it boil for 2 minutes (this step is very important). Remove from the heat, and stir in the peanut butter and vanilla until it is well mixed. Quickly blend in the oatmeal mixture.
Beat by hand until it is thickened, a few minutes. Drop by teaspoonfuls onto waxed paper. Store in refrigerator until firm or keep in another cool place.