Sia went undercover the day before Thanksgiving (November 27) to treat some surprised shoppers to a heartwarming surprise.

The 43-year-old stopped at Walmart and T.J. Maxx in Palm Springs to pay for shoppers' groceries and items. She went from register to register at the check out lines paying for their items.

Most of the shoppers had no idea that it was the secretive pop star until after the fact. Fans reported that she went by "Cici" and that she told the lucky shoppers that she recently won the lottery.

Because of Sia's wigs that cover her face, shoppers believed the cover story until one fan shared a video identifying the singer. "So @Sia paid for my groceries today thank you so much," a Twitter user wrote. "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!"

See the videos and accounts from shoppers, below.