I'm from California. Dude is all we call each other here. Although for some reason I have the habit of calling people I do not know "captain" or "doctor." Like, "Hey, captain! You can't just cut!" or "'Scuse me, doctor... you dropped this." I don't have any names for the female variety of person... so I call them captains and doctors too. But people I know? It's always "dude."