President Barack Obama pumps up a gun designed by Joey Hudy, left, of Phoenix, Ariz., left,  to shoot a marshmallow in the State Dining Room of the White House in Washington, Tuesday, Feb. 7, 2012, during the White House Science Fair. Obama hosted the second White House Science Fair celebrating the student winners of a broad range of science, technology, engineering and math (STEM) competitions from across the country. (AP Photo/Susan Walsh)
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