Wise old dog

I am inquisitive and have a good memory, and I am suspicious of things I have not seen before. When I was young I used to bark at people with something white on their head, white hair or hats. I also barked at people with umbrellas, motorcycle helmets and once at a man with a child on his shoulders. It looked like a tall two-headed creature. I embarrassed my mom and dad the most, however, when we all went to the airport to meet a friend, and while we waited outside the terminal I saw a black man for the first time. I went wild. Now, however, I am a lot wiser, and of course I happen to be black myself!