Why would girls stare at a guy they don't know?

I would think that it would obvious. When a girl stares at you or glances then that means that they think you're hot. I remember this one time in high school I had teased this one girl and she laughed then every time I ped her in the hallways she would glance at me(check me out). She even did this one time when she was with her boyfriend. At that time her boyfriend was asking her what she wanted to do later and then I ped by and she starts fixing her hair and straightening her shirt. It was priceless. So there you go, you seem hot or "cute" to them so they stare at you. You're only getting mad about it because you didn't know what it mean, but now you know, so enjoy it.