First off, I am not a cowboy. (Big surprise, innit?) Just as my name isn't Brat.
However, there is a wonderful book by Josephine Tey titled Brat Farrar, in which the main character's name (sort of) is Brat Farrar. And he is an English orphan who ran away to America and became a cowboy for a while. (Then he breaks his leg and goes back to England and impersonates some rich orphan who apparently committed suicide and has a twin and would be about to inherit a lot of money if he weren't supposed to be dead, only they never found a body so that's suspicious, AND THERE ARE HORSES, but none of that pertains to the matter at hand.)
Anyway, hence the cowboy.