zavirivati

1. (u + acc.) to peek; to peep into
   Deca stalno zaviruju u kuhinju da vide šta se kuva. — The kids keep peeking into the kitchen to see what's cooking.
   Ne volim kad mi neko zaviruje u telefon. — I don't like it when someone peeks at my phone.
2. (into others' affairs) to pry; to snoop
   Prestani da zaviruješ u tuđe živote. — Stop prying into other people's lives.

The perfective is zaviriti.