Now that I have a child, I find that I can talk (seemingly) to myself in public and sing quite loudly while driving and no one looks at me funny. They all assume I am talking to LP. In fact, every once in a while people have complimented me for talking to her and have reminded me how important it is to talk to my child as much as possible.
So far this has not caused any uncomfortable situations, but I am sure I have come close since I occasionally use this technique for some passive aggressive messaging. For instance, there was a house in our neighborhood that had Christmas decorations up in April. I don't mean just turned-off lights, I mean several flags hanging from the side of the house with Santa on them, a menagerie of plastic figurines and a wreath on the door. So, to "justify" this to LP during our walk I made up a story about how they must be waiting for a loved one who is a soldier to return from the war to celebrate Christmas. Hey, maybe it was true.
The unabashed singing might even be worse. One of my favorite tapes when I was growing up was this Cabbage Patch Kids "rock opera". There was nothing rock or opera about it, but it was a story told through song and I loved it. I made my entire family listen to it on lots of car trips (if you are brave and know my mother, ask her to sing a few bars of "Otis Lee" to you). In fact, I wore the tape out. As a gift a few years ago, the Hoos found it on CD online and ordered it for me. I admit, I listened to it before LP arrived; but now I can listen to it and sing along (it is amazing how I still know all the words 20 years later) all the time! I am not sure if LP even likes it yet, but she will!