What does it mean when a guy stares at you while talking to his friends?

Okay so A guy has been staring at me for awhile and at lunch he stared while I walked by him and well I was talking to my friend's and I look over at him and he look's at me then his friends starting looking over the side of the table to stare at me too. And when I sat down I noticed he was staring at me while talking to his friends? He didn't laugh, point, or smile but what does this mean?
What does it mean when a guy stares at you while talking to his friends?
Post Opinion