There are several synonyms for the phrase "dollars to cobweb," which means a highly unlikely event or outcome. One synonym is "slim to none," which implies an almost impossible probability. Another similar phrase is "needle in a haystack," emphasizing the difficulty of finding something specific in a vast and chaotic situation. "Pipe dream" is another appropriate synonym, emphasizing the unlikelihood of success. When describing a specific situation, phrases like "uphill battle," "long shot," or "Herculean task" can be used, all conveying the sense that success is highly unlikely. Overall, these synonyms effectively convey the sense of improbability and difficulty associated with "dollars to cobweb".