Hey!It's ok to self-talk,unless it damages your relationships with others or harms someone.I talk to myself a lot,most of the time I make jokes and laugh at them by myslef D.It happens to me on the streets too,not so often cause i sing all the time.It's like you are speaking your thoughts out loud,if you want to control it just write it down every morning on a paper or on your phone and try to be conscious about it. I can almost guarantee,you can control it,since you are the master of your body!
God bless!