My Cup Runneth Over With Bad Behavior

(My professor and I are meeting at my favorite coffee shop for tutorial. At this point, I have studied there at least twice a week all year and the staff all know me and my order by sight, so I am a consistent regular. We walk in and take a table; my professor has, among an armload of things, an empty to-go coffee cup from another shop in the city.)

Me: *at the counter* “Hello, can I have my usual, please?”

Manager: “Only if you get THAT out of here!”

Me: “…I’m sorry?”

Manager: *points at the empty cup among my professor’s things* “THAT. I WILL NOT HAVE IT IN MY STORE!”

(Confused and rather mortified, I went back to my professor and sheepishly relayed this message, which she found as odd as I did. I got my order and we finished our tutorial there, the offending cup having been thrown away as the manager continued to give us suspicious looks. It had been my favorite place, but after that I did not go back again.)