I talk to myself all the time.
When I'm driving, I talk smack about the other drivers. Especially if I'm anywhere near a rotary, since no one uses the things right.
I talk to myself when I'm doing something with several steps. I go through the steps out loud as I work through them. It helps me to be sure that I've done everything.
And of course, sometimes I make sarcastic comments to myself. Sometimes I make such comments about people I'm talking to them, while I'm talking to them. For some reason no one's ever punched my face for this, although I couldn't tell you why not.