10 Genius In-Jokes In The Simpsons

Season four's "The Front" sees Bart and Lisa write an episode of The Itchy & Scratchy Show and submit it under Grandpa Simpson's name, in turn getting him hired as a staff writer.

The entire episode is a brilliant, relentless slew of in-jokes about both the animation industry and The Simpsons itself, and perhaps the stand-out gag occurs when Bart and Lisa visit Itchy & Scratchy Studios.

While being toured around, Lisa mentions how expensive it must be to produce cartoons, to which company head Roger Meyers Jr. replies, "Well, we cut corners. Sometimes to save money, our animators will reuse the same backgrounds over and over and over again."

And just at that moment, anyone paying even the faintest attention will surely notice that the hallway they're walking down is itself recycled, featuring the same cleaning lady and door on a loop.

It may not be subtle, but it sure is clever - and more importantly, very funny.