A parody of "The Strawberry Roan," in which the boss hires the cowman to ride a "big Brahma bull" in a rodeo. The rest follows the original: The rider winds up being thrown, and "high-tail[s] it back to that old Flying U."
This is reportedly Curly Fletcher's parody of his own "Strawberry Roan." (Fletcher in fact wrote several such parodies; see also "The Castration of the Strawberry Roan.") Roud appears to lump the pieces. - RBW