A couple's dog "randomly" started showing aggression to their babysitter, so they set up a hidden camera and captured the babysitter slapping and cussing at the baby! What a good dog.
http://foxnewsinsider.com/2013/09/13/heroic-dog-saves-baby-abusive-babysitter
http://foxnewsinsider.com/2013/09/13/heroic-dog-saves-baby-abusive-babysitter