In the series' pilot episode, protagonist J.D. sees Janitor fixing a sliding door that is stuck, and suggests someone might have stuck a penny in the door. Janitor immediately accuses J.D. of sabotaging the door, and swears revenge. For the rest of the series, Janitor makes it his personal mission to torment J.D. with insults, mind games and practical jokes. In the season eight finale, J.D. admits to accidentally sticking the penny in the door; Janitor replies he saw J.D. do it and began torturing him because he failed a "test of character" by keeping silent about it. Some of Janitor's practical jokes have been on the severe side, such as destroying J.D.'s bike (twice), trapping him in a water tower, stranding him in the middle of nowhere, and tricking him into robbing a couple's house.