You always felt someone gaze on you but you don't see anyone, you think its just your imagination and you ignore it

At School You felt someone behind you and you turn around and saw John, your best friend so you told him about how you felt someone gazes on you, You didn't know that John was stalking you...

"Oh my, I'm so sorry to hear that, you can give me your room key so I can watch out for you" He smile innocently