Hold an infant in both hands, arms extended overhead, and the baby will laugh as you do.But if you make a sudden sound, “whoops!” and act like you are dropping the baby, his little eyes clamp shut as both of his hands ball into tight little fists. Now, if little Wilbur has a gun in hands, that little index finger, along with all the fingers and thumbs of both hands, will curl shut-and there will be a “bang!”