Corn snakes are naturally timid, like most snakes their primary defence is flight (running away not flying - well, slithering away not running). If they can't get away and they are scared, they will vibrate their tail against something to make a noise. If you really really try hard to piss them off you might get a nip but it's never happened to me or my kids, and they don't have much in the way of teeth anyway.
Corn snakes are naturally timid, like most snakes their primary defence is flight (running away not flying - well, slithering away not running). If they can't get away and they are scared, they will vibrate their tail against something to make a noise. If you really really try hard to piss them off you might get a nip but it's never happened to me or my kids, and they don't have much in the way of teeth anyway.