Person 2: What happened?
Person 1: Well, I saw this girl I know at the other side of the park coming toward me; naturally I smiled and waved.
Person 2: So, what was the problem?
Person 1: Well, she smiled back, but we were still separated by a good fifty metres. I didn't want to keep eye contact because that would have looked weird, and I could hardly smile again; I just had to look at the floor for a little while... Was so awkward...
Person 2: Ah I see, classic example of not leaving an appropriate greeting distance.