This has actually been done and worked for a TD in a high school game.
http://www.youtube.com/watch?v=1YnnnnyMjCw
What confuses the other team is the fact that the center does not have to snap the ball to the QB between his legs, he can snap it around the side if he so chooses.
Perfectly legal and definitely a good trick play... although kinda a lame to pull on a bunch of 10-12 year olds though.