In the first scene, he is just an average "cowboy" with a lasso etc. In the second scene, he is a "cowboy" in the sense that he is part human, part cow.
this actually doesn't really make much sense. First, I have never heard this saying, it's not standard in our day to day humor, it may be an arcaic reference. And what exactly would a cowboy have to do with genetic research, or what would be funny about that?
