In fact, Sia continued the ruse by telling her newfound friends that her name was "Cici", that she had just won the lottery and wanted to spread the luck.
"Who's next?" says the generous celeb as she moves with credit card in hand over to another register.
Then she paid for everyone's groceries.
One woman claiming she was among the cornucopia of customers to have their groceries covered by the nine-time Grammy-nominee shared her experience on Twitter, writing: "So @Sia paid for my groceries today thank you so much!" Buckles tweeted. "The heart and handsome soul you have for paying for everyone!"
A Twitter post showed a 15-second clip of the "Chandelier" performer hugging strangers while donning an olive-coloured overcoat, a blue-and-purple tie-dye sweater and black trousers - notably sans her famous black-and-white wig.
The star's act of kindness later came to light on social media, when photos and video emerged.
They also posted a 45-second video that was taken by another fan that featured Sia holding a flower bouquet that another customer gave her and asking "Who's next?" I'm sorry for telling everyone once I realized who you were! "But this kindness must be acknowledged!" wrote the grateful fan.
The fan apologized for spilling the beans once she realized that the mystery shopper was actually a famous singer. But, when it comes with national news recognition, then that's called publicity.
Popular Australian singer Sia, has shown her love for random strangers at a mall she recently went shopping at.
Singer Sia showed up at the Walmart "in disguise" on the American holiday of Thanksgiving - but really, she just looked like a normal person.