I just witnessed one of the most pitiful, yet archetypal conversations. It was between two work colleagues who knew each other by sight, probably by name and maybe even had a history of working together on projects. However, they hadn't realised, until the conversation got going, that they didn't really know each other personally:

Him: Hi there, I haven't seen you in ages, how are you.
Other: Yeh, not bad.
Him: Yeh, it's been ages.
Other: Yeh.
Him: So... er... how are things.
Other: Yeh, not bad.
Him: Yeh.
Other: Hectic.
Him: Hectic.
Both: Yeh. [pause]  [walked away from each other without saying anything else]