Cara Delevingnestopped by “The Tonight Show with Jimmy Fallon” last night to talk about her upcoming movies “Paper Towns” and “Suicide Squad” — and to give house band The Roots a run for their money. FortunatelyFallon just happened to have a live microphone waiting, because it turns out Delevingne can drop a pretty sick beat. She even slowed it downso Tariq Trotter could jump in with some freestyle. And she did it all whilewearinghigh-waisted, wide-legged pants by Balmaincovered in so many crystals Fallon remarked they must weigh more than him.