"Sling the bull" is an idiomatic expression that means to talk or boast at length without necessarily telling the truth. Some synonyms for this term include "spout off," "beat around the bush," "pretend," or "blow smoke." It's important to note that these words all carry slightly different connotations, depending on the context in which they are used. For example, "blow smoke" may imply an intention to deceive, while "spout off" suggests a more general tendency to speak loudly and opinionatedly. Overall, there are many ways to describe someone who is slinging the bull, and the choice of word depends on the specific nuances that the speaker wishes to convey.