I heart SCRUBS: Trivia

Through the first season, the cast and crew, especially writer/creator Bill Lawrence, were so sure that the series would be canceled by the end of the season, that a plot twist was created for use when they'd have a forced series finale. This plot twist noted the fact that the Janitor, Neil Flynn's character, never directly spoke nor was spoken to by any other character than JD, Zach Braff's character. Therefore, the Janitor would be a complete figment of JD's imagination. This idea was kept up into the second season, still in fear of cancellation, until Flynn asked Lawrence to be able to finally interact with another actor on the series. (Although Elliot actually throws a cup at him in the 6th episode and sarcastically says "SORRY!", in episode 11 he gets punched on the balls by a little girl and in episode 15 the janitor teases the nurse with the vacuum cleaner)