What is an unboy?

Today Taylor was attempting to pull Buddy our dog on his long, red leash. Taylor called him an "unboy" several times. With slight irritation she would say, "Oh, Buddy, you unboy." I was curious to know what an unboy meant in Taylor language. I asked her and she explained, "Buddy was not following me so I called him an unboy."
So now you know; if you ever have someone who is not following you, I guess you could call them an unboy!
Sarah