Pharrell and Gwen Stefanirekindled their musical ties as they took to the stage on NBC's The Voiceto perform the P produced smash of the 2000s "Hollaback Girl." All you late-80s babies no doubt recall a time when this Neptunes anthem reigned supreme over the air waves, making it a staple on that mix you gave your high-school sweetheart and likely the soundtrack to your 2004 summer. The performance was a warm-up for the duo's residency as judges/coaches on the singing competition next season, where they'll decide the fate of the next generation of contestants. Watch Pharrell and Gwen perform their collaborative hit "Hollaback Girl" on The Voice below.