What Language Do Doggies Speak?

I'm teaching "D is for Dog" this week. In Japanese the sound a dog makes is Wa Wa. Not so far from Bow-Wow. And a puppy is called a wa-chan, even though a dog is called an inu. After teaching them D and then Dog, I point to the cat and say meow, and then point to the dog and start barking. I use more of an "arf" than a "bow-wow". I run around the room, barking and jumping, and then come to the front of the room again and start to wag my hind end and pant like a dog. And repeat. They quite love it, and a few will even imitate me. Then we get back to work, and they get their crayons out and color the "D is for Dog" copy for the day. I then go to each individual child and ask what is this? pointing to the D, and again for the dog. If the child answers in Japanese, I don't tell him that he's wrong, I just ask for the English word. Well, I got to one certain little boy and asked him my questions, and he answered "wa-wa". So I asked him to tell me the English word. Instead of saying dog, he jumped up and said "arf arf" and wagged his little hind end. And sent me and his mother into convulsions of laughter. He looked a little confused and hurt. Wasn't that right? Which only made us laugh harder. I got a grip on myself, and had him repeat the word "dog" a couple of times. I sure hope he gets it, or it could be quite embarrassing for him when he gets older.