I spend an unsettling amount of time talking to myself. Usually, I am just singing whatever song is in my head at the moment. I'll sing in the shower, sing while doing dishes, or quietly mouth the words to a song while walking (I don't actually make sounds though. I don't want people to think I am talking to myself. Right?). If I am caught in the act, I usually start humming some fictitious tune to mask my song selection. So, if you see me humming some atonal ditty, I was probably just singing "Oh Sherrie", and imagining myself on stage pushing the new Journey singer off the stage, donning a leather jacket, and high-fiving Neil Schonn as he busts out into a face melting guitar solo.
When I am not singing arena rock anthems to myself, I am legitimately talking to myself, and that's sort of scary. I do have a curious habit of fixing onto a specific word and repeating that word over and over, never tiring of it nor realizing how often I am repeating it. Sort of like Tourettes Syndrome. Often, oddly, the word is in a foreign language. Now, I am not that proficient in any foreign language, but I have enough of an ego to convince myself that I can speak a few of them with a convincing accent (Spanish, French, and German, namely). Therefore, when I fix on a word, I pronounce the hell out of it. Sure, it's probably the wrong pronunciation, but dammit, it sounds good to me.
I also talk to myself when I am angry. I mean, I have to be fucking pissed off, but when those rare occasions arise, I will blabber to myself incessantly. Usually I am saying what I wish I said to the person who pissed me off. Or, I am saying what I want to say. But I am not just coming up with pithy comebacks or stinging criticisms. I am forming situations. I form complex situations, filled with contingencies and motives and subterfuge, around myself and the offender. Like a master chess player, I start thinking of retorts to moves that haven't even been played yet, never mind imagined by the (imaginary) interlocutor! I can get myself so heated up that when I bring myself back to reality, I have no choice but to laugh out loud at how ridiculous I am acting/thinking. But I try to remember my comebacks, just in case.