"I refuse to listen to your meaningless nonsense".
I just told my dog to "sit down". Boy was she confused.
Anyone who's ever trained a dog will understand my inadvertent mistake. I told her to both "sit" and to get "down", two very different commands. I immediately realized my mistake and apologized, and then got her a treat, since apologies don't carry as much weight as biscuits.
This verbal confusion happens often. My husband commits a similar verbal slip when he tells her to "go down". The word "go" she knows is associated with leaving the house to go for a walk or go in the car. Telling her to "go down" results in cognitive dissonance. She can't decide if she's supposed to lie supine on the floor or head for the door.
Dogs can understand a great many words and even concepts, but they can't really understand that a word might have two different meanings. I'm constantly on the alert for those dual meaning words, and I try not to use them. I've almost stopped myself from telling her to "Shake!" after a bath when she jumps out of the bathtub—she immediately presents a paw instead of shaking vigorously as she longs to do.
I'm also alert to the adjective "good". I used to habitually exclaim, when we came in from a walk, "We had a good walk!", which made her wonder if the walk was going to get a treat, like "good girls" do. Now I declare it a "nice" walk, and leave it at that.
The other day I created more confusion, again, inadvertently. When I'm heading out to the gym, I put on my sneakers and the dog comes out, wagging her tail, since she knows it might mean a walk. "You can't go; I'm going to the gym" I tell her, and she dejectedly returns to her spot under the desk. So though she probably doesn't understand what a gym is, except that she knows I come home smelling slightly sweaty and warm, she does know she can't go there. The other day we met our young friend down the street, who has a new rescued border collie. Her name, I learned, was Jem, so I turned to my dog and made the introduction. "This is your new friend, Jem," I said to her, and then wondered why she gave me such a dejected look. Was she sad that the little girl had a new canine playmate? No, jealousy hadn't entered her mind. Of course, I realized as we walked away—"Jem" and "gym" are the same word to her, since she can't see the different spelling.
As I've written previously, I've made a conscious effort to teach my dog human language. But human language is very contrary and confusing. Just like humans who are bilingual, I think my dog prefers her own language.