Gettin' wiggy wit it! Natalie Portman crashed into Sia's a cappella rendition of the '60s hit "Iko Iko" which she performed alongside Jimmy Fallon on The Tonight Show on Wednesday, January 27, complete with classroom instruments. 

But this version of the awesome, recurring musical bit was even crazier than usual, as the entire gang (including house band The Roots) wore black and white and sported monochrome wigs!

The Australian singer and songwriter, who is about to release her seventh album, This is Acting, led the singalong, with Fallon on the spoons and Star Wars star Portman banging wood blocks.

Sia, 40, whose own oversized wig covered her face in her trademark style, also wore an enormous white bow in her hair as she harmonized with gusto, dancing on her white cube, before ending with a little surprise!

Watch the whole unmissable moment in the video above.

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