There's a secret to choosing the perfect lipstick shade: Just get your boobies out.

Excuse us, but it turns out the secret to finding your perfect lipstick shade has been hiding inside your bra this entire time. 

According to a recent episode of The Doctors, women should match their lipstick to their nipple colour in order to find their most flattering shade.

Dr. Travis Stork – a man who I have not once seen actually wear lipstick – revealed this information to a live audience who shrieked in horror at the word ‘nipples’.

"NOT NIPPLES!" one woman could be heard yelling.

"However will I check the colour of my nipples? Goodness gracious... how crass."

Twitter promptly responded to the breaking news, with some claiming that they'd discovered this beauty hack years ago.

Will be searching for the nipple shade lipstick now

— #EqualRights&Justice (@MystikalMirage) 1 May 2017

Yall about to have me at sephora with my titty out trying to find a lipstick shade to match my nipple https://t.co/vyqX9bGMMU

— baby posty (@jxnni98) 1 May 2017

I definitely think my nipple color is my best shade of lipstick. How are we just finding out this magic?!

— ThunderKat (@Kath3dral) 2 May 2017

I've been saying I want a lipstick color the same as my nipple color for THE LONGEST https://t.co/7BF8lr6ggN

— J☹️ (@jjordannnnn) 1 May 2017

The theory goes that nature knows best, and nipples are an indication of what suits your skin tone. Whether they're light pink, brown or red, our nipples are said to be one to two shades darker than our skin colour, so they offer the perfect natural palette.

It's important to note that this does not make it okay to get your boobies out in Priceline, or present your right nipple to the make up artist at Mac. You definitely should not do that.

But it's worth having a look, and comparing the lipsticks you gravitate towards. You might find it's something you do instinctively.

It also explains why blue lipstick has never, ever looked good on anyone. And if it does - they should probably see a doctor about some concerning coloured nipples.

It turns out tiny nipples are in fashion. We discuss on Mamamia Out Loud.