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.
(..) Honestly, just relax. I'm fine. Cut the bullshit. I know you left detention. I know you left the hotel room in Washington. I know you sneak out of this house every night. That's not fine. Peter, you have to tell me what's going on. Just lay it out. It's just me and you. (..)2017 Spider-Man: Homecoming
(..) You in? TONY: Peter Screws the Pooch... Instead, you hacked a multimillion-dollar suit... ...so you could sneak around behind my back... - Is everyone okay? TONY: No thanks to me? Those weapons were out there, (..)2017 Spider-Man: Homecoming