In short, not only was it surprising to be greeted in person with such enthusiastic words, but it was doubly surprising when the person reciting these words displayed the same kind of disengagement as, say, the checkout clerk who utters the words 'Have a nice day' while her expression indicates that it's really a matter of total indifference to her whether you drop dead in the parking lot outside ten seconds from now.
David Foster Wallace, The Pale King
humor, humour, humourous