If there a stranger and staring at me kind of weird I'd probably raise my eyebrow to ask, "what are you staring at?" If it's a friend I'd be all whats up and smiling. But it's really easy for me to stare at peoples eyes when I'm talking, lying, and smiling etc. Just can't do it when I'm sad because I wouldn't want anyone to notice it. But then it's gets awkward to stare at them for to long.
Smack them in the face and say sorry. They say 'why did you do that?' You say 'You looked in my eyes!' Make sure you are not looking in their eyes when you say that or get ready for a smack.