Hello Break One's Promise means not doing what you promised to do , for example if you promise a friend a Car at Christmas but when Christmas comes and your friend asks for the Car you say , sorry I cant give you a Car anymore. Eat One's Words: If you boast that you are going to win a competition and end up losing then you are " eating your words" . This is used in situations when one has been so confident of achieving an outcome or goal but ends up losing or faililng at the outcome. In an election a Candidate could boast of winning but ends up losing.