Note: This works best when you have an upgraded automatic shotgun. At first you will only have a gun. Shoot the small head as much as possible until you get to the part where the clowns start going crazy. There is a brain in the bottom corner of the box where the first clowns come out back to the Boss. Shoot the legs out from the under the clowns while flipping to make them crawl When they are on the ground, shoot the Boss.