Hi, I'm reading a memoir, 'Bittersweet' written by Matt McAllester. <The news editor sent me to a strip names Sunrise Highway. A motorcyclist had been showing off to his friends on the highway. He was balancing his helmet on his forehead. It slipped ontho his nose and he rode into the back of parked truck. "That's what we call a cleaning-the-gene-pool story," said another reporter." How can be a 'paked truck' on the highway? And what does this 'cleaning-the-gene-pool stroy' mean?