I do it. It's how I work things out. I interview myself. I practice important conversations ahead of time. I fascinate myself with myself. This doesn't sound the same as schizophrenia or turrets. I have bipolar disorder, but my brother and my cousin do not so it's not necessarily a mental illness thing. They do the exact same thing. Rest easy. I don't imagine you'll be stalking down the street raving about talking chickens anytime soon. Some people just think better outside their heads.