A guy walks into a doctor's waiting room... A guy goes into a doctor's waiting room, and sees four old men. One of them suddenly shouts "39", and the others all start laughing. "That's strange", he thought. " 23", shouts another man, again followed by hysterics. "46" a third man shouted followed by further laughter. "Why does everyone keep laughing at these numbers?" the guy asked. "We are regulars here, and tell the same jokes so often we decided to number them, watch this...17", and everyone started laughing again. "Go on, have a go" the fourth man said. "Alright... 53" he said. Everyone started crying with laughter. "Why was that so funny?" "We haven't heard that one before"