Annabel Crabb explains why the kangaroo on Australia's coat of arms has to have a really big bulge.

When you see our national coat of arms, you might stand up a little straighter. Looking at that kangaroo and emu, you just feel a surge of patriotism.

It reminds you of childhood trips to Canberra learning about the Senate when inside you were dying to go to Questacon. Of searching the skies for the Southern Cross. Of  election day democracy sausages. Of big hairy balls.

Ummmmm, hang on. What?

You’ve probably looked at that pair of native animals hundreds of times and never noticed the obvious smacking you in the face. Mr Kangaroo is in a fact a Mr. And you can tell by looking between his legs. (If you dare.)

He stands proudly atop Canberra’s parliament house at the front of the building, danglers dangling.

And naturally, once we heard about this grand display, we were dying to hear why parliament house made this ballsy design move.

Fortunately, this week on No Filter, Mia Freedman is joined by an intrepid explorer of the halls of Parliament House. ABC journalist Annabel Crabb spills the beans (ahem) on this national icon.

While making her new TV show The House, Crabb spent 10 months inside Australia's political hub, getting to the bottom of our most important decision making processes, the people behind the parties, and the peculiar quirks of this grand building.

But obviously once you hear this smart and accomplished woman start to talk about balls, you don't want to hear about politics anymore. You just want to know WHY.

You'd think a respectable journalist might get a bit testy when Mia wanted to talk about such smut, but Crabb was perfectly happy to give an explainer.

"One quite famous Australian artist John Coburn put in a design for one of the coats of arms, and apparently it was rejected on various grounds including the design problem with it," Crabb says.

"The design did not fulfil the requirement for the kangaroo on the coat of arms to be 'visibly male.'"

A post shared by Katy Milliken (@katymilliken) on Jan 24, 2017 at 8:37pm PST

Cracking a stubby open with a kangaroo scrotum has got to be the most Aussie thing that has ever happened.

And visibly male, of course, means a big hairy kangaroo scrotum on full display.

"It is not cool to have your country represented by a lady roo," she says.

Apparently our overlords thought it would be too emasculating for Australians to be represented by a kangaroo that isn't a bloke.

Politics, eh?

But we will be eternally grateful to Annabel Crabb for bringing this fact to our attention.

Want to read more about big hairy balls? Of course you do. Click here. 

Want more Annabel Crabb goodness? Watch this video.

Interested in Australian politics told in a hilarious way? This should do it.

For more secrets from inside Parliament House, listen to the full episode of No Filter with Annabel Crabb:

To subscribe to the show, go to apple.co/mamamia