Matt Groening shared The Simpsons joke they were forced to scrap from show due to strict rules

The Simpsons creator Matt Groening has said that there's a joke they've dropped from the show because of when the show is on TV.

The classic animated comedy has been going on and on and on for decades now and they've done pretty much every joke under the sun, to the point that they've managed to predict so many things over the years.

You might think The Simpsons writers room have a crystal ball with unerring accuracy but they've admitted that when you throw so much at the wall over the years some of it is going to stick.

Of course, some of the jokes become self-fulfilling prophecies as people try to make Simpsons jokes real.

However, according to the show's head honcho, there's a gag they no longer show which they'll leave up to other animated comedies.

He really is wearing nothing at all. Nothing at all. NOTHING AT ALL (Fox/Disney)

According to the Metro, Groening explained that because of when it's on at night The Simpsons will now not show Homer's bottom.

He said: "Historically, The Simpsons has been on Sunday night at 8pm. There are things you can do and can’t do at 8pm that you can do at 8:30.

"For a while, we’d show Homer’s butt and then they said we could no longer do it, but Family Guy could, because they were on at 8:30."

In earlier seasons of The Simpsons ,there would be a few moments where Homer's bare bum would be shown and you might not have noticed that it doesn't really get much of an airing these days.

Groening added that 'a lot of unusable material is pitched' whenever they're doing an episode with a lot of Moe in it, as he's been used for a lot of The Simpsons darker material.

The Simpsons doesn't really show Homer's bum any more, but we can (Disney/Fox)

Elsewhere, The Simpsons creator said that other animated shows had more leeway to be 'edgy and dirty and weird'.

He said: "I feel like other shows actually can be edgy and dirty and weird so much better than we can.

"Like Family Guy, or South Park, or Rick and Morty – we’re not gonna out them them.

"For me, it’s like, let’s do what we do, let’s just do emotional, observant, humanity based comedy, and satire.

"Stuff that really made the show exciting in the beginning – and not try to out-Family Guy Family Guy, because you’re never going to do it."

As for how The Simpsons could one day end, executive producer Matt Selman said he hoped that if it did end, there wasn't some special grand episode and The Simpsons denouement would be 'a great family story' and 'doesn't feel like it needs to wrap up anything'.