All the talk about what it meant for Doc Holliday to say, "You're a daisy if you do" and what daisy in that time period meant has little to do with the definition of the word daisy or deusy (doozy). It was the context of the word usage of the time. Another widely used phrase of the time was... "he's pushing up daisies", meant a person was dead. I believe Doc Holliday was meaning if you shoot at me you'll became a daisy...or you'll be pushing up daisies. In other words he meant, you will be the one to die! Just as the saying, "I'll be your huckleberry" was a humble way for Doc Holliday to say I'll fight you or I'm the man for the job. Doc was a man who had no problem with acting as though he were not as good as another man but knowing he was truly a better gunslinger. Huckleberry was a term often used in the time to measure the weight or worth of something. A huckleberry versus a persimmon or apple, a larger or more substantial fruit. It symbolically began to refer to a smaller, more humble thing in comparison to something larger, but more vain. Mark Twain used it to name his character, Huckleberry Finn, to assert that he was smaller (socially speaking) in comparison to Tom Sawyer in many ways but he was a more humble character.