As a teenager she would 'sneak' out (of her house/apartment) at night to visit her boyfriend.
I'm going to 'sneak' a smoke. [=I'm going to smoke a cigarette while nobody is watching]
She took a 'sneak peek' [=a secret look] at the birthday presents hidden in the closet.
(..) We've done a lot of things to this lady. And if she ever wakes up, we'll do a whole lot more. But one thing we won't do is sneak into her room in the night like a filthy rat and kill her in her sleep. And the reason we won't do that thing is because that thing (..)2003 Kill Bill: Vol. 1