As I left the YMCA tonight, Rachel, the pleasant woman at the entry desk waved to me and said, “Have a good evening!”
I jokingly replied, “Have a good rest of your life!”
She frowned and even looked insulted.
I said, “Since we are trading wishes and hopes, I decided to give you the biggest one I could think of.”
It is funny how, in the expression, “Have a good [X],” the X signals approximately how long it might be until you think that you will see each other again. Thus, the BIG wish that I uttered, which ostensibly seems more generous, suggested that I would never see Rachel again (or maybe even that I didn’t want to ever see her again). Conversely, “Have a good afternoon” often signals that the speaker hopes to contact the other person that same evening (or at least, soon).