I'm hoping you can help decipher something that happens on a regular basis.
When I'm walking somewhere, it is not unusual for me to look directly into a guy's eyes (usually a younger guy) and for him to nod at me without saying something or (since I live in the south now) for them to acknowledge me by saying "yes sir."
Tonight something different did happen. I looked at a redheaded guy, he looked up at me, then said "what's up," and then smiled at me. He served to be in a hurry however.
What's your interpretation of all this?