Ed Kemper had a dark fantasy life as a child and teenager: he performed rituals with his younger sister Allyn’s dolls that culminated in him removing their heads and hands. Some of his favorite games to play as a child were “Gas Chamber” and “Electric Chair”, in which he asked Allyn to tie him up and flip an imaginary switch, and then he would tumble over and writhe on the floor, pretending that he was being executed by gas inhalation or electric shock.

Sources: “Serial Killers: The Method and Madness of Monsters”, Vronsky, Peter (2004) / Wikipedia Ed Kemper page / Photo of Allyn Kemper (18 years old) from the Soquel High School yearbook, 1969