Got this one the other day!
ME: Sir, would you like a drink with your breakfast?
PAX: Ill have a tea please.
ME: Sorry sir, unfortunately we have run out of potable water (dont ask, its a long story but lets just say we coped despite a total lack of even flush water in the loos) so hot drinks are unavailable. I do apologise however can I offer you some juice?
PAX: Its ok, its not your fault, Ill just have a Coffee instead!!!!