Two very elderly ladies were enjoying the sunshine on a park bench in London. They had been meeting at that park every Sunday for over twenty years... chatting, and enjoying each other's friendship.
One day, the younger of the two ladies, turns to the other and says, "Please don't be angry with me, dear, but I am embarrassed, after all these years. . .What is your name? I am trying to remember, but I just can't."

The older friend stares at her, looking very distressed, says nothing for two full minutes, and finally with tearful eyes, says, "How soon do you need to know?"