President Barack Obama invited a broad spectrum of established and budding scientists to the White House for a science fair, including some people with North Carolina ties.

When one of the student presenters -- an eighth-grader from Arizona named Joey -- displayed his air cannon, the president couldn't resist learning more.

And when the president learned the air cannon could fire marshmallows up to 176 feet, he talks Joey into firing the cannon. Indoors. In the White House.

The rest, as they say, is presidential history -- and a potential Secret Service headache.