reporter: 25-year-old linnea claeson of sweden is in her element on the handball court. practice, the professional player and her team function like a well-oiled machine. linnea has been playing handball since childhood. now she plays in denmark's first division. she's on backcourt offense and the key player on her team. but linnea is a fighter off the handball court, as well. to many, she's a hero in the fight against sexual harassment. and she's had more than her share of hurtful experiences on the internet. linnea: things like this have happened both to me and my girlfriends. sexual innuendos on the internet, and offline, as well. reporter: over and over, she's received suggestive and degrading postings on her social media accounts. a total stranger sent her this one -- >> hey deary, you go for scarfing? i'd like to gradually strangle you beneath me until you slowly run out of air. how's that sound? a little hot? reporter: linnea says this kind of harassment is widespread on the internet -- almost a daily occurrence. men photograph their own genitals and send them to