If you try to unbind someone or something that isn't bound, without specifying a type of binding (and maybe even with one), and that person or mob isn't bound, you get the "help" message for unbind. It makes it seem like you entered the parameters incorrectly, or that it doesn't support parameters. I'd expect some sort of "So-and-so isn't bound, dumbass!" message instead.

(You can use that exact message if you want. I don't mind.)