Blowing smoke is a phrase that refers to someone who is exaggerating or lying. While there may not be a direct opposite to this phrase, there are words that can be used to describe someone who is honest and straightforward. Sincerity is a word that describes someone who is genuine and honest in their actions and intentions. Authenticity is a word that is used to describe something that is true to its origins or is genuine. Honesty is another antonym for blowing smoke, as it describes a person who is truthful and transparent in their dealings. All of these words are great alternatives to use when describing someone who is not blowing smoke.