(I have just completed a transaction and given the customer their coffee.)
Me: “Have a great day!”
Customer: “What did you say to me?”
Me: “I said have a great day.”
Customer: “Well, that’s impossible. I am an English teacher. It’s impossible to have a great day. Something will always go wrong to prevent ‘great’ from being the correct adjective to describe ‘day’. I find you wishing me the impossible insulting.”
Me: “Have a decent day?”
Customer: “Thank you.”
(The customer sits down to eat near the register and opens a book. Another customer orders and pays.)
Me: “Have a great day!”
Original Customer: “I heard that!”