Can you turn on the A?

So today in the car, Grins said "Mommy, can you turn on the A?" "The A/C?" I asked. "No, the AB." was the reply. We went back and forth for about 5 minutes; I kept trying to figure out what he wanted, and he was so frustrated that I didn't understand. He finally said "The ABCD!!!" and then it hit me - he wanted me to play a "CD". I love the way kids perceive things.