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.
(..) Let me pack a bag and make sure my health insurance is paid up. How are we gonna get past them? I think they're looking for threats trying to come in... not people trying to sneak out... so, I think we're cool as long as we stay quiet. Sorry! We're... We're guarding, too. (..)2013 Percy Jackson: Sea of Monsters