You saysomething about turtles... No wait, wrong smalltalk.
Seriously though, small talk is fleeting. You pick a generic subject (Something like: what's up? How are you doing? (if the person is doing something interesting) What are you doing? How does it work? Why are you doing that?). Just ask questions, don't get too personal at first. Pick up on clues, ask about what you hear. Keep it light. Backchannel a bit ("oh, I see", "uh-huh", nod, etc), but don't overdo it.
Oh, and practice, preferably with people that you know well.
No, this is just a wonderful bit of obsolete hacker history. Unless if you mess with retro-architecture for fun (like old PDP machines, be they emulated or real), then it's somewhat relevant.
Yes, modern compilers do loop unrolling nowadays, so Duff's device doesn't really have a use. But it's certainly a wonderful bit of history. I found Duff's device when I was researching coroutines in C.