Best Coast’s Bethany Cosentino joined Kendrick Lamar last night at the Portland installment of the vitaminwater uncapped music series, singing backing vocals (and whispering some raps) on "No Make-Up (Her Vice)" from Section.80, which Lamar had never done live before. Watch the performance above and see more photos from the show—where Lamar also pulled a fan onstage to rap a couple songs—here. For live clips and performances from other uncapped shows, visit the vitaminwater YouTube channel.