Billie Eilish has revealed her "biggest secret" as she makes her Tiktok debut, and fans simply can't get enough...

Billie Eilish has never shied away from being her true self.

And, much to the excitement of fans,  following the release of her new single, the star finally joined TikTok!

But it seems one of her videos has stirred up quite a reaction...

After eagle-eyed fans were quick to spot something unusual in the clip.

Aged just eighteen, Billie has taken the music industry by storm.

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She's been writing and creating her own music since she was incredibly young, and has risen to fame with her huge hit album When We Fall Asleep, Where Do We Go? that was released in March, 2019.

She's known for being somewhat of a quirky character...

Billie was home-schooled, so she didn't get the chance to interact with others of her own age apart from her siblings until she started to make waves in the music scene, which has given her something of a unique outlook on the world.

It also gives her music a different sound...

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Many are pretty shocked that such a young person could create such hauntingly catchy tunes - and such suggestive lyrics.

Her debut album, When We All Fall Asleep, Where Do We Go?, ranked at number 1 in the charts.

Most artists have to release a couple of albums and dedicate their lives to promoting their work before they are even recognized as an artist, but then there’s a lucky few, like Billie, who reach superstardom on their first attempt. When the album was released, she wrote, “This album [means] the world to me please take care of it."

But that wasn't even the first time that we saw her climbing the charts...

Her introductory EP, Don’t Smile at Me, went all the way to slot fourteen, and has already been awarded gold, an achievement that many artists can only dream of receiving.

But, it's safe to say, Billie is as famous for her image as she is for her music...

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She doesn't dress like your typical eighteen-year-old girl, that's for sure.

She is known for rocking some pretty out-there looks...

Like this full white suit complete with Powerpuff Girl embroidery, which she pairs with some signature tiny sunglasses.

Or what about this full green ensemble?

We have to say, love it or hate it, you can't deny Billie's commitment to her look - and that's not something many of us are brave enough to pull off.

And Billie doesn't just experiment with fashion...

The star is no stranger to getting creative with her hair - opting for more out there looks and colors to fit her quirky aesthetic.

Her neon-green roots seem to have become her trademark...

And they don't seem to be going away anytime soon.

But it turns out that there's a reason behind Billie's quirky look...

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Her choices in fashion - which strongly consist of baggy, oversized clothes - are picked to protect herself from her global audience body-shaming her and judging her on her natural appearance.

Speaking in an interview last year, Billie explained these choices...

"That’s why I wear baggy clothes," she said. "Nobody can have an opinion because they haven’t seen what’s underneath. Nobody can be like, ‘she’s slim-thick,’ ‘she’s not slim-thick,’ ‘she’s got a flat a**,’ ‘she’s got a fat a**.’ No one can say any of that because they don’t know."

And we honestly don't blame Billie for having this attitude.

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But sadly, people have already attempted to exploit and body-shame the teenager. Even when she was as young as fifteen, online trolls were trying to sexualize her for no apparent reason.

It's terribly sad that the singer has to put up with this treatment...

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And it is a harsh reality that young women in the spotlight are always targeted by older people.

Many of these people have tried to blame her lyrics.

But let me get this straight. Just because there’s a line in her song “bad guy" that reads: “bruises on both my knees for you," it’s now acceptable to start sexualizing her? I really don’t see the correlation here.

Billie has the right to sing about whatever she wants...

There's no excuse for sexualizing a young woman... Or any woman of any age, for that matter.

But, when discussing the topic, Billie has said in the past that she doesn't want to remain covered up forever.

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"I'm going to be a woman. I want to show my body," Billie told Elle in an interview last year. "What if I want to make a video where I want to look desirable?"

She said that, upon turning eighteen, she wants the option to sometimes reveal her body.

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But she understands the repercussions a move like that could bring. "I know it would be a huge thing," she said in the interview, adding, "I know people will say, 'I've lost all respect for her.'"

Well, in December last year, the pop sensation turned eighteen...

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And we have been yet to notice any changes in her fashion sense and clothing choices.

Until more recently.

The star has recently been pictured without her trademark baggy attire and the internet went crazy... with many unbelievably fat-shaming the teenager.

And, after the snaps began doing the rounds on social media...

People were quick to call out those shaming and objectifying the eighteen-year-old.

But that doesn't seem to have stopped the star.

And her music video for her most recent single Therefore I Am even featured her enjoying some fast food - seemingly in a statement against the body shamers.

And, as her new single hit the charts...

Billie joined TikTok!

And her latest video on the popular app seems to have already made quite an impression...

Because reactions immediately came pouring in after eagle-eyed fans spotted a key detail.

During the clip in question, Billie talks about one of her main party tricks...

Which - long story short - happens to be the fact that to fit the end of a ukulele in her mouth. "Do you guys remember when I was 15 and I fit an entire ukulele head in my mouth? Shall we see if I can do it again? I very much doubt it but I shall try," she says at the start of the TikTok.

She then proceeds to fit the entire ukulele head in her mouth...

While breaking into fits of laughter.

But, musical instruments aside, fans were quick to notice something else about the clip.

Billie's natural skin texture happened to be on show, seeing her ditch the filters and dark lighting often seen on her Instagram stories.

While, of course, it's totally up to Billie whether she opts for filters in her videos or not...

It's nice to see someone which such a big platform normalizing skin texture!

Check out the video for yourself below.

For more on Billie, scroll on to see why she was furious at the reaction to the video of her taking her clothes off...