Sydney Sweeney spills out of a tight corset as she belts out songs, fires thongs and dollar bills into the crowd and dances with Lance Bass in behind-the-scenes moments from Stagecoach

Sydney Sweeney let her hair down in style at Stagecoach Festival in California over the weekend. 

The Euphoria actress, 28, attended the star-studded country music event to promote her new Syrn lingerie line, and on Thursday, she shared a behind-the-scenes look at the fun had in her brand's pop-up saloon. 

Sydney looked sensational as she modelled two $269 corsets from the brand - which she launched earlier this year - that perfectly hugged her hourglass curves. 

Proving to be the life and soul of the party, Sydney was up on the stage belting out country songs before firing thongs from her brand into the crowd. 

Sydney had also made up personalised dollar bills with her face on as keepsakes for the crowds. 

Bringing some celebrity pals in for the party, Sydney was seen duetting with Lance Bass before dancing around the stage with Shaboozey. 

While at the festival, she also surprised fans by appearing on stage during Diplo's set and throwing more thongs into the crowd. 

'Let's get some of these panties right here,' Diplo announced as he welcomed her, before telling revellers the underwear was for 'the ladies, not the guys'.

A photo of Sweeney and Diplo was posted via the underwear brand's Instagram Stories on Saturday evening, with the caption, '@diplo Thanks for stopping by!!!'

While Sydney had a great time over the weekend, the festival was forced to issue an emergency evacuation due to high winds.

According to a report from Just Jared, festivalgoers on social media said there was an evacuation message announced over the speakers, displayed on stage screens, and on the corresponding livestream.

'Emergency Evacuation. The festival has been postponed until further notice. Please move quickly and calmly to the nearest exit,' attendees were directed in a statement typed over a red screen.

But less than an hour later, an updated message said, 'The show will resume. We are working to open doors and prep the site for your safety. Stay tuned for updates.'

The SYRN Saloon was stationed at the Citrus Courtyard near the Honky Tonk Bar and was open from '12pm to last call,' per Stagecoach's website.

A note on the site promised: 'We're bringing your favorite dive bar to the desert, reimagined the SYRN way.'

It also teased: 'Ice-cold SYRN cocktails, karaoke for the brave (or a few drinks in), classic dive bar games, and panty giveaways.'

On the first day of the annual three-day event, Sweeney wowed fans by singing alongside country singer Bailey Zimmerman.

She reposted a clip from internet personality Zarah Kelleher on Saturday, who was dressed in SYRN'S $59 Cowgirl Crush Frill Top in the color Limoncello / Love Me Not.

Kelleher gushed in the caption of a video, 'Sydney Sweeney is the sweetest girl ever.'

The Housemaid star shared the snippet via Instagram Stories and wrote that she 'was so excited to see girlies wearing @syrn.'

She added: 'Everyone looks so good!!!' and added a string of drooling emojis.

Sydney's day two outfit was comprised of pieces from SYRN'S My First Rodeo collection.

Earlier this year, she opened up about her mission for the brand, insisting she wants to ensure every piece fits well and works on a 'beautiful range of body types.'

She told Cosmopolitan magazine in January, the company's launch month: 'My designers are all women, and I have an amazing diverse team.

'My models are a beautiful range of body types. I'm always like: "I want to see it on everybody." 

'I can't be the only model. I need to make sure everyone feels really good in it.'

Sweeney emphasised: 'If I wouldn't wear it, I wouldn't want to make it.'