Sydney Sweeney's saucy on-stage stunt shocks crowds during surprise appearance

Sydney Sweeney, 28, stunned crowds with a saucy on-stage move when she made a surprise appearance with Diplo, 47, at the Stagecoach Country Music Festival.

The Euphoria star threw handfuls of underwear out at fans in the audience of the DJ's annual HonkeyTonk set.

Well, not just any underwear, but ones from her new lingerie line, SYRN, which launched in January this year.

Watch the video above.

As Sweeney joined Diplo on stage, she brought up a plastic bag full of SYRN pieces.

"Let's get some of these panties right here," Diplo announced to the crowd.

The DJ was quick to clarify the underwear was "for the ladies, not the guys."

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Dressed for the country saloon stage, Sweeney wore a baby blue corset fringed with lace ruffles and white cowboy boots.

She styled her signature blonde tresses in soft curls with a deep side part.

Sweeney's lingerie brand also shared "scenes from day 1 at the SYRN Saloon" with Instagram images showing the actress performing the same on-stage stunt on the first day of the festival.

The actress kept her ensemble western-themed, wearing blue denim overalls, a white top and brown knee-high boots.

Eagle-eyed fans noted Sweeney was wearing a dainty necklace with an 'SB' charm, seemingly a nod to her boyfriend Scooter Braun, 44.

The Housmaid star's underwear stunt comes just weeks after the couple made their relationship Instagram official as Braun reshared a black-and-white photo of the pair cosied up with the text "lucky bastard".

Sweeney's SYRN promotion raised eyebrows online, with some labelling it "weird" while others say they "respect the hustle".

Sweeney is no stranger to controversy with the actress embroiled in drama after a "tone-deaf" tagline from an American Eagle advert sparked global firestorm last July.

She appeared in an ad for the popular US jeans brand which used the tagline, "Sydney Sweeney Has Great Jeans".

While some saw it as an innocuous play on the words 'jeans' and 'genes', others argued it hinted at genetic superiority.

Sweeney addressed the drama last December in an interview with People, saying she was "honestly surprised by the reaction".

Brushing off the criticism, she returned this April in another American Eagle advert modelling a pair of denim cut-offs.

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