Here's one perk of going through your potentially awkward tween years in the national spotlight: you get to mingle with one of the world's most popular teen idols. Last night, Sasha and Malia were the envy of American girls everywhere, as they accepted hugs and high fives from Justin Bieber at the annual Christmas in Washington concert. Jennifer Hudson, Cee Lo Green, and Conan O'Brien were on hand too, singing songs at the concert that benefits the Children's National Medical Center. But it looked like the whole first family caught a case of Bieber fever, as the pop star got some love from the president and first lady. All three Obama girls, Michelle, Malia, and Sasha, looked chic for the evening. See how the first daughters are growing up now with pictures from last night's concert!