Gwen Stefani Sings ‘Hollaback Girl’ At Blake Shelton Show

The "Sweet Escape" singer made a surprise appearance at the Watershed Festival over the weekend

Gwen Stefani surprised an entire crowd of Blake Shelton fans at the Watershed Music and Camping Festival that went down in George, Washington right before the weekend.

The "Sweet Escape" singer took the stage midway through her boyfriend's headlining set Friday evening and really stole the show. (Sorry, Blake!)

Watch the Shelton crowd go "BANANAS" in this video from the festival: