My Neighbour is causing me a Problem?

Hi..My name is Prity .I am 16. My problem is there is this young guy..who's room falls parallel to my room...thing is wenever I open my window for a breathe of fresh air..I see this guy..either walking naked in his room after a shower..or sometimes he is even Masturbating. Its not lyk he does it intentionally..he doesnt even know he is being watched. I can stop from looking there as his window is straight parallel.My frnzz said dat i should talk with him..I even went at his house..and wen I opened his bedroom door which was already open..there he was ..lying onhis bed stark naked..Now I cant even talk to him due to embarassement..wat do i do??