True example of the above:
I had been given a task by my manager, in such a way that my coworkers could hear that it was something important I had to get done ASAP.
Half an hour later, I'm heads down working, with earphones in. Very obviously coding. Coworker taps me on the shoulder. "Yes?" "Why aren't you chatting with us?"
I'd like to say I made some clever remark, but at the time I was speechless.
(Please note that I do engage in normal small talk at other times. )