In my part of Alabama, we called the Hog Nosed Snake "Puff Adder" ( maybe "Puffing"). As a young man, I sometimes kept snakes as pets. The "Puff Adder" was a very interesting snake that employed unusual defensive techniques. Being harmless, it had to depend on subterfuge for it's defense. When threatened, it will "puff" up like the photo. A normally marked one( as opposed to the black one in the photo) has spots that look like eyes when puffed up, to mimic a larger snake. It is often said they look like a cobra, but it is unlikely that any threat would be familiar with cobras. If that doesn't work, they will roll over and play dead. If you roll them back to their stomach, they will immediately roll back over. If you persist in rolling them back to their stomach, they will defecate. The smell is so intense that I never tried to find out what they would do next.
Mike