Stop Staring at Me

What constitutes "staring at someone"? Is there a standard time of unbroken eye contact that defines it? Leering, ogling, checking out, glaring, adoring; these are all staring sub genres with good and bad connotations, so perhaps its not time, but style/quality that defines it? Though when it boils down, I don't want this dude looking at me for any amount of time.