In all the time--a year now--I've been working at the public library, I've probably told people to have a good night (or "a good one") a thousand times.  Every once in a while, they will ignore me, but usually, they will say, "You too" or "Thanks" or "The man in the moon has chickenpox."  It means nothing, but is a social nicety that nobody complains about.

Except one guy.
The other night, as people were leaving for the night, I told one particular dude to have a good night, and he was having none of it.  He stopped in his tracks and turned on me, like one of those vicious dogs behind a fence (at least I hope they're behind one).  
"Don't tell me that," he said, rather animatedly.  
"Sorry?"  
"Don't say that!" he shouted, which got the attention of every other patron about to leave the library (heck, even the girl at Circulation looked up from her phone for a moment).  I could tell that I was dealing with either an unstable person or a royal piece of crap.  "You don't tell somebody to have a good night!"
But he was standing there, waiting for a reply.

"What should I say?" I asked.
He took a step toward me (what law enforcement would refer to as a lunge) and said, "You say goodbye!"
It was absurd enough I nearly laughed, but the man was disturbed enough already.  "Goodbye," I said.
"Thank you!" he half-yelled, then turned and left the library.
And that's it.  I didn't later learn that he'd shot up a yogurt shop or a pickleball court (one just opened here in town, so that would be extra unfortunate) or anything.  It was just a weird thing that happened to me.  Now that I've shared it with you, go ahead and have a nice day.