Have a Good One

"Have a good one."

You hear this phrase, I suspect, mostly from sales clerks as they hand you some change and scowl, or maybe smile weakly. I can't fault them on the scowl. After all, they have a tedious job. And typically in the United States they are not even allowed to sit, as they are in many countries, at least in Germany (I saw it). And Germany is not exactly known as a slackers' haven. But I digress.

Have a good one.

I loathe the expression.

Have a good what? A day, a bowel movement, an apex of pleasure, an assignation, a life, a death, a time, an evening, an afternoon, a betrayal, a laugh, an interview, a meal, a journey, a wrestling match with a hyena from Borneo, a marathon, a flight of fantasy, a root canal, a trip to Neptune, a session of electroshock therapy, an audience with the pope, a nap, a meeting with a client, an acupuncture session, a spot of tea, an instance of amnesia, a just dessert, a singular moment of unparalleled exhilaration, a bout of ennui, a satori?

Which is it?

Tell me.

Please!