S04E10: Enemy In-Law

Mr. Krabs' mom is dating again, and it seems like things could be serious. Krabs tries to be happy for his mother, but he is absolutely horrified when he learns that the secret paramour is his arch-rival Plankton! Convinced that this just another trick aimed at getting the family formula for Krabby Patties, Krabs tries to reveal Plankton's schemes and break up the ill-favored fling.