YouTube sensation Rebecca Black, 14, joined her mentor Katy Perry, 26, for an acoustic performance of "Friday" in L.A. over the weekend.

Once they finished their duet, Perry gave Black a hug and told the crowd: "Thank you so much, Rebecca. That was our moment. We love you Rebecca! Give it up!"

Black recently made a cameo in Perry's "Last Friday Night (T.G.I.F.)" music video. Still riding high on the success of "Friday" (and her current single, "My Moment), Black also picked up a surfboard for Choice Web Star at Sunday's Teen Choice Awards in Universal City, Calif.