You are laughing with your friends here in the canteen, while eating lunch. While talking at them you notice him again, eating alone while reading a book.

You looked at him while smiling. So you just admire him from a far, you don't know if he has a girlfriend or what but you like him.

While looking at him he looked at me too so you looked away and talked to my friends again, you didn't know he is smiling while shaking his head while looking at you.