I've been thinking about something lately that I've never really paid much attention to.
Here's the situation: You're walking down the street, and you see an unfamiliar girl headed towards you in the opposite direction. She's a casual, normal-looking person with a placid expression on her face. What kind of eye contact do you usually make in this kind of situation?
(I used a girl for this example because I know for a fact that none of us would give a crap if it was another dude. Ahaha, am I right?)