The phrase "pulling a fast one" is often used to describe someone who is trying to deceive or trick someone else. It is a slang term that can be used in a variety of situations. However, there are several antonyms for this phrase that suggest the opposite of deception or trickery. Honesty, integrity, transparency, and sincerity are all words that could be used to describe the opposite of "pulling a fast one." These words suggest that someone is being truthful, trustworthy, and straightforward. By using these words, we can describe behavior that is more ethical and responsible.