It's Me or My Dog

Emily loves to watch just about every show on Animal Planet, including a British show called It's Me or the Dog. In the show, a dog trainer helps rehabilitate problem animals. I walked in today and saw Emily watching the show. I asked her what was wrong with this dog and she explained:

Emily: "This dog is really bad. He's always humping people."
Me (thinking I'd misunderstood what she'd said): "He what?"
Emily: "Humping people"
Me: "What does that mean?"
Emily: "It means he climbs on people's legs and doesn't let go."
Me:"Oh." (Not sure of what to say), "Ok."