I heard someplace that Fiery and Snuffy were a couple of notoriously spooky cattle, and when they jumped, the herd would stampede. That is why the line about them is preceded by "ride around the little dogies, ride around 'em slow." Don't do anything to stir them up, because Fiery and Snuffy are just itching to start another stampede. It was a song sung to the cattle at night by the hand assigned the job of riding around the herd to keep them quiet until morning.