By KELLY MCCARTHY via GMA - Pop singer Sia paid it forward for a group of unsuspecting shoppers at a Walmart.

 

Adri Buckles shared the sweet video on Twitter Thursday and thanked "The Greatest" singer for her random act of kindness.

 

"The heart and beautiful soul you have for paying for everyone," she wrote.

Shoppers at the Palm Springs store didn't immediately recognize the superstar since she is known for her oversized wig that hides her face.

It's unclear how much money the singer spent on the groceries, but according to ABC News affiliate WBRZ, Sia went to multiple registers and asked to pay for people's items.

Buckles added, "I’m sorry for telling everyone once I realized who you were !! But this kindness must be acknowledged!!!"