Talking to yourself is not only not idiosyncratic, it's actually so universal that it's more a linguistic activity than a psychological one.
I love getting caught doing embarrassing things, once when the microwave was going, I pretended I was casting a spell on it, until my girlfriend (at the time) walked in on me.
Once I was listening to music, so I had headphones in, which could have been playing something funny (they weren't, but anyway), I thought of a joke and started laughing uproariously to myself, and an elderly woman coming the other way shielded a little girl from me, as if she sincerely thought I was a raving loony. I see so much humour in it that I adore that it happened.
Of course though "you think you're so clever and classless and free", in reality appearances have a huge effect on me (and a bigger effect on anyone than you'll hear most proclaim), but most of it's under the surface.