The Simpsons (1989): Season 28, Episode 16

28 - 16: Kamp Krustier

When Bart and Lisa return home abruptly after a traumatic incident at Kamp Krustier, they put an end to Homer and Marge's romantic encounters. Without sex to distract him, Homer becomes a more productive worker and caring husband, but Marge misses the old Homer. Then, Bart and Lisa return to camp to confront the source of their trauma. Blackboard: 'We're the only house where the Christmas tree is still up'.