1)...on ones own or with friends is to go out for a night on the town - clubbing, pubbing, whatever takes your fancy.
2)...with a special someone who is your girl/boyfriend on a date.
2)you know john's stepping out with lucy?!
Locale: Western Canadian prisons.
Sometimes the best thing to do when you roll into a new joint is "step out" on the first spoke so people don't take you for a bitch.