A greeting with force
I got on the elevator this morning coming up to my desk at work, and there was a woman there already. I said "Good morning" and she said it back. A nice interaction.
When the elevator doors opened on her floor, I said "Have a great day!" A typical thing to say to a stranger as they exit the elevator, I think.
But then I started to think about how that is really a command. You MUST have a nice day! You have no other choice, as I've just told you to do it. HAVE A GREAT DAY (or else -- maybe could be implied or assumed but probably not by normal people).
Just struck me in the moment that this common saying isn't suggesting or hoping people have a good day, it's demanding that they do. Maybe that isn't such a bad thing after all.