Australian pop star Sia carried out a very generous deed for Walmart shoppers under the guise of a woman who had just 'won the lottery' - warming the hearts of people on social media and spreading some much-needed holiday cheer.

The good-natured shopping trip went down on Thursday, as Sia - unrecognizable without her trademark giant wig - tried to remain under the radar as she paid for the groceries belonging to several customers at a Walmart in a Palm Springs, California.

The moment was captured by fans and has since been shared on social media:

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When she arrived at the grocery chain, the Chandelier hitmaker told customers and staff her name was Cici and spun a story about having won the lottery as an explanation as to why she was picking up the tab for a bunch of strangers.

A short clip was posted to Twitter showcasing the moment the singer-songwriter hugged delighted shoppers at the store who were bowled over by her generosity, as were commenters online.

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"I love that she did this not for recognition of showing kindness, but just actually being a kind person," wrote one Twitter user. She didn’t want people to know who she was, or why she was doing it

"Now THAT is one ultra-classy lady and no mistake," added another.

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Sia is seen clad in a long coat, a blue-and-purple tie-dye sweater, and black pants. I guess she can easily pull off these random acts of kindness as many people simply wouldn't know the star's face due to the fact she can often be seen performing in her iconic black-and-white wig.

Check out another video which captures the touching moment Sia is met with gratitude by the Walmart customers:

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One of the shoppers who says her groceries were of those covered by the singer, wrote on Twitter: “So @Sia paid for my groceries today thank you so much!! The heart and beautiful soul you have for paying for everyone!! I’m sorry for telling everyone once I realized who you were !! But this kindness must be acknowledged!!!”

The above clip, which has garnered over a million views, shows the Never Give Up performer holding a bouquet of flowers, presumably given to her by one of the shoppers.

“Who’s next?” the talented artist asks as the previous transaction is completed.

Woman tells Walmart customers she's won the lottery and pays for their shopping - turns out it was Sia