Who said it's the plumber?

The phrase "It's the plumber" is often attributed to a scene in the 1979 film "The Jerk," where the character Navin Johnson, played by Steve Martin, humorously refers to a moment involving a plumber. The line encapsulates the film's comedic style, which relies on absurdity and misunderstandings. If you’re looking for a specific context or reference, please provide more details!