Sail under false colors is a phrase that means to hide your true intentions and deceive others to gain an advantage. Some synonyms for this phrase include imposture, pretense, fraud, deceit, and deception. They all refer to a person or group acting in a dishonest manner to gain an unfair advantage. To disguise oneself or one's purpose can also mean to masquerade or to put on a false facade. Other colloquial synonyms for sail under false colors include pulling a fast one, conning, bamboozling, duping, hoodwinking, and swindling. Overall, these synonyms all refer to the act of deception and fraudulent behavior.