I used to work with a guy called Rod who managed to say this several times a day. He could just magically work it in, eg. "Report's due Friday? I'm on it. But there's so many other things due, I don't know whether I'm Arthur or Martha at the picture show this week." Sometimes I'd walk past his desk and he'd be muttering it quietly though contentedly to himself: "Oh deary, deary me. I don't know if I'm Arthur or Martha at the picture show. Oh, deary."