The phrase "bag of wind" is commonly used as an insult for someone who talks too much without substance or meaning. There are a variety of synonyms that can be used to replace this phrase, including "empty talker", "gasbag", "windbag", "long-winded", "verbal diarrhea", "blowhard", "chatterbox", "jabberer", "motor-mouth", "rambler", and "yapper". All of these synonyms convey the same idea of someone who talks excessively without saying anything worthwhile or of substance. It is important to be aware of and use these synonyms in an appropriate way, as name calling can be hurtful and unproductive.