The person could be thinking of something funny, or he/she is in good mood or the person is smiling at you.
He probably has a crush on you and is too nervous to approach you. Why don't you try introducing yourself : )
When a girl is constantly Hitting and being mean to you and smiling she most likely flirting with you but if she is not smiling she is probably serious which means she does not like you. It goes both ways.
Your crush may be getting up the nerve to finally talk to you if they are are now smiling.
It means that your crush noticed you, and wants to talk to you but might not know what exactly to say.
the guy's a loony. and a pedo. he MUST be crazy. and he definitely doesn't have a crush on you
he probably wants to go out with u
She probably has a little crush on you. or she's wondering what's on your face.
It sounds like they have a crush or they were just looking at you. If they do it a lot, they probably like you. Try talking to them a little more, and be a judge as to whether they are into you.
he is happy
i think someone has a crush
He'd probably like it if you talked to him too, maybe he's even got a crush on you. You should try smiling at him when you catch him staring. Try to look him in the eyes when you do it, or if you can't do that smile and look away shyly, maybe play with your hair or bite your lower lip.
He's either in like too so he embarrassed and giving you the I like you too and I embarrassed silent treatment or he mad you like him more than a friend and giving the disappointed silent treatment.