Once, a famous dramatist George Bernard's play was being staged. He invited Sir Winston Churchill to watch the play. As a matter of courtesy, he sent in a cover with a note saying, "One ticket for you and the second one for your friend, if at all you have one friend indeed!"
Churchill sent him a rejoinder stating, "Due to pressing engagements, I will not be able to attend the show. Hence, please excuse me. If you send tickets for the second show of your play then I will surely come, if it ever runs for the second time!"