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.
(..) I know for a fact that some of the officers go to that brothel in Mole's Town. I wouldn't doubt it. Don't you think it's a little bit unfair? Making us take our vows while they sneak off for a little Sally on the side? - Sally on the side? - It's silly, isn't it? What, we can't defend (..)2011 TvShow: Game of Thrones Title: Cripples, Bastards, and Broken Things Season: 1 Episode 4