"You are no Daisy"
The use of daisy in conversation was not something that Doc Holliday made up. It was a fairly common in the late 1870s. If you look through old newspapers from the time period, there are plenty of references to people being daisies because they were doing something wonderful for their town.
Despite his formidable reputation as a deadly gunslinger, Doc Holliday only engaged in eight shootouts during his life, and it has only been verified that he killed two men. Still, the smartly dressed ex-dentist from Atlanta had a remarkably fearless attitude toward death and danger, perhaps because he was slowly dying from tuberculosis.
In 1879, Holliday came to New Mexico and settled in Las Vegas where he opened a saloon with a partner. Holliday spent his evenings gambling in the saloon and he seemed determined to stress his health condition by heavy drinking. Holliday also enjoyed the company of the dance hall girls that the partners hired to entertain the customers.
On July 19, 1879, a former army scout named Mike Gordon tried to persuade one of Holliday’s saloon girls to quit her job and run away with him. When she refused, Gordon became infuriated. He went out to the street and began to fire bullets randomly into the saloon. He didn’t have a chance to do much damage–after the second shot, Holliday calmly stepped out of the saloon and dropped Gordon with a single bullet. Gordon died the next day.
The following year, Doc Holliday abandoned the New Mexico saloon and joined his old friend Wyatt Earp in Tombstone. There he would kill his second victim during the Gunfight at the O.K. Corral in October 1881.
His hard drinking and tuberculosis eventually caught up with him, and he retired to a Colorado health resort where he died in 1887. Struck by the irony of such a peaceful end to a violent life, just like in the movie, his last words reportedly were “This is funny.”