What is hidden in 3D image?

During preseason training, a college football lineman married one of the team's cheerleaders. The coach was a bit surprised and remarked to his star football player, "You are such a big, burley guy. Why in the world did you marry such a tiny, petite woman? She is no bigger than your hand."
"That's right, Coach," replied the lineman. "But, she's much better!"