1x18 - The New Addams Family

Fester reading an article by Dr. Pierre LeBlanc titled ""The Dangers of a Happy Marriage"", gets the family to try to help make Gomez and Morticia fight with each other. When he fails, he calls up Dr. LeBlanc who comes over and tries to steal Morticia from Gomez. So, Gomez challenges Dr. LeBlanc to a duel.