This dog is in a bit of a pickle.
He very much wants a bite of a cow's ear, but he doesn't want the cow to know. It has to be a covert nibble, apparently. (Maybe a cow's ear tastes better if the cow doesn't know you're nibbling on it?)
The most amusing part is how the dog is able to quickly appear as if he wasn't just trying to take a bite out of the cow's ear by shutting his mouth and giving a quick lick. "Oh, no, nothing to see here. I was just ... umm ... yawning! Yes! I was just yawning. So sleepy on this farm. Hey, what's that over there?!"