Singer Gwen Stefani makes a surprise appearance, performing onstage... News PhotoAdult,Adults Only,Almost Acoustic Christmas,Appearance,Arts Culture and Entertainment,Belt,Black,Black Belt - Fashion Item,Black Blouse,Black Shoe,Blonde Hair,Blouse,Bra,California,Celebrities,Checked Pattern,Checked Trousers,Christian Louboutin - Designer Label,Christian Louboutin Shoe,Collar,Cuff,Dancing,Footwear,Gibson Amphitheatre,Gwen Stefani,Long Sleeved,Music,One Person,One Woman Only,People,Performance,Pointed Toe,Pump - Dress Shoe,Red,Red Trousers,Sheer Fabric,Singer,Singing,Skinny Belt,Stage - Performance Space,Tartan,Tied Bow,Trousers,USA,Universal City,Up Do,Vertical,WhitePhotographer Collection: Getty Images Entertainment 2012 Imeh AkpanudosenUNIVERSAL CITY, CA - DECEMBER 08: Singer Gwen Stefani makes a surprise appearance, performing onstage with Bush at the 23rd Annual KROQ Almost Acoustic Christmas at Gibson Amphitheatre on December 8, 2012 in Universal City, California. (Photo by Imeh Akpanudosen/Getty Images)