There was an expectant father who had spent quite some time waiting for the offspring to arrive - at his in-laws place. He was absolutely positive that his wife was going to present him with a boy and wouldnt hear of anything else. As his leave balance had gone into the red, he told his father-in-law,

"When my son comes, do not call up office and say that I have become a father of a boy. Then I'll have to shell out a lot for parties, etc. Just tell me that the clock has arrived. This will be our code for the arrival of my son."

The offspring does arrive one day, but it's a daughter. The father-in-law now thinks, "If I tell him that the clock has not arrived, he'll misunderstand that some thing has happened to the baby and come rushing over."

So he sends the message, "The clock has arrived, but the pendulum is missing."