The polka-dot-wearing actress makes a cheerful arrival to the Late Show with David Letterman. Plus: Blake Lively, Gavin & Gwen, Nick Jonas and more

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DRESS REHEARSAL

Rocco DiSpirito and Karina Smirnoff get ready to rumba on the L.A. set of Dancing with the Stars before Monday's episode. Unfortunately, despite the warm-up, the team only earned 16 out of 30 points from the judges.