Columbus is not a very aggressive person. He does nearly anything he can to not get in any altercations. However, when he was at Pacific Playland, he needed to be aggressive. In order to get to Wichita, he had to kill a zombie. This was no ordinary zombie though, it was a clown, which is his biggest fear. He took a hammer from one of the smashing games at carnivals and hit the zombie in the head with it. This was one of the most aggressive scenes that involved Columbus in the whole movie. Although zombies aren't technically alive, this is still very aggressive, especially for someone like Columbus.