The Birth Of Assumption

(A guy comes in, buys his stuff by credit card, as I hand him his bags and receipt:)

Me: “Have a nice day!”

Customer: “What? The h*** did you know?”

Me: “Sir?”

Customer: “The f*** did you know it was my birthday? You see my ID in my wallet or something?”

Me: “Uh… sir? All I said was have a nice day.”

Customer: “…”

Me: “…”

Customer: “Not ‘Happy Birthday?'”

Me: *trying VERY hard not to smirk* “…No.”

Customer: “Well, this day’s off to a good start…”

Me: *smiling sympathetically* “Have a nice day, sir. And Happy Birthday.”