The four of them belted out Stefani's "Hollaback Girl" in perfect harmony ... Gwen Stefani and James Corden for the popular "Carpool Karaoke" segment on "The Late Late Show with James Corden." ...

Gwen Stefani's "Hollaback Girl" is a sassy spelling lesson, so it's fitting that she'd finally take it into the classroom. In a video from November 26, Stefani joined Jimmy Fallon and The Roots in ...