NEW YORK -- A 15-year-old boy lost his arm when he and friends were reportedly trying to subway surf on Monday in Queens. MTA officials have been warning younger passengers against the risky trend of subway surfing, which is gaining popularity on social media, CBS2's Christina Fan reported. The blood-stained platform at the Roosevelt Avenue-Jackson Heights station was a gruesome reminder of the dangerous consequences. "They just don't understand the meaning of life. That's what the problem is with a lot of these young people who are doing this kind of moronic, ridiculous thing," said Everett Jennings, of Rego Park....