Dilbert mentions the forced nodding and smiling in the office several times. And there's a very funny Seinfeld monologue about making up new ways of greeting people that you already greeted when you arrived, once you run out of eyebrows rising, !$%*!$% smirks, handwaves and grunts.
in regards to the comic, it's like when people greet you by saying "How's it going" instead of hello.. and then they keep walking rather than wait for the answer...