Go here and here if you don't know this meme. And this is the official White House page for the photo caption.
President Barack Obama jokingly mimics U.S. Olympic gymnast McKayla Maroney's "not impressed" look while greeting members of the 2012 U.S. Olympic gymnastics teams in the Oval Office, Nov. 15, 2012. Steve Penny, USA Gymnastics President, and Savannah Vinsant laugh at left. (Official White House Photo by Pete Souza)
How cool is our President?! =D