Movies
You know, what this room needs is a really big oversized poster of Atlantic City...oh look, you've got one.
— Charlie · So I Married an Axe Murderer

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
A backhanded jab at bland décor dressed up as helpful advice. The speaker pretends to suggest something obvious, then reveals it's already there, mocking unimaginative taste. The joke lands in the gap between offering an idea and instantly withdrawing it as redundant.
Context reviewed