Justin Bieber protégée Madison Beer showed off her ‘whale tail’ while clad in an $820 Dior ‘Oblique’ bikini beneath khaki cargo pants following her performance Saturday at AYU Dayclub in Las Vegas.

Popularized in the nineties, a ‘whale tail’ in fashion is defined as the shape a thong makes while peaking out of a skirt, shorts, or pants.

The 22-year-old Long Island native was joined inside Resorts World Las Vegas by her boyfriend of nearly a year, TikTok star Nick Austin.

The 20-year-old ‘content creator’ – who’s lived in the $12M Hype House mansion – has called Madison the ‘love’ of his life, his ‘best friend,’ and ‘soulmate.’

Austin gushed on March 5: ‘Every day with you feels like I’m dreaming, which I might be. I love you. Forever n ever n ever!’

On Saturday, Beer gave her brunette locks an Ariana Grande-style boost with a faux-nytail and she rocked large hoop earrings.

The Emotional Bruises songstress – who boasts 50.4M social media followers – captioned her Instastory: ‘Twas very fun, thank u again Vegas!’

Beer was said to have previously romanced Jack & Jack’s Jack Gilinsky, model-photographer Brooklyn Beckham, and Field Trip Records co-founder Zack Bia.

On the Fourth of July, the homeschooled millennial celebrated her new single Reckless reaching 20M streams on Spotify and the music video has received 3.7M views.

‘Thank you for all the support on this song,’ Madison said in a video premiere vlog last Tuesday.

‘I don’t even want to get into it right now, but this song was not approved by many people [at Epic Records] and you guys have proved my gut instinct right.

‘Because I knew you guys would love it. It means a lot, because it helps so much in the future. Because there are people who not necessarily didn’t believe in the song but they were just not about it.’

Beer has been hard at work recording her second studio album – dropping by the end of 2021 – and she’s already come up with the name for it.

The Everything Happens for a Reason singer is next scheduled to return to AYU Nights on July 29 before performing August 27-28 at the sold-out Reading & Leeds Festival in England.