And it has different effects on them with Kim being forced to tell the truth even if it is ugly and embarrassing and it makes Kim look silly and without discipline (because she has no inhibitions) while Ron is able to be sincere about the truth and it makes him more popular. For Kim this truth ray shot came at a terrible time because not only did she botch an interview but her dad's superiors are coming over for a visit and she blurts out clear facts that are best left unsaid and not only seemingly ruining the visit but putting her dad's job position in jeopardy. Fortunately the scientist Kim and Ron rescued earlier is the over the other superiors and saves the day by declaring Kim a hero and confirmed the truth ray story as true and saves Mr. Dr. Possible's career in the process. Eventually the truth ray's effects wear off.
An overall funny and enjoyable episode (half episode actually) that spills the truth on why it is best to withhold the truth or even lie at times. This isn't one of Kim's best moments but one of the highlights of Ron's.