Just because you only live once, that doesn't mean you should involve yourself in risky behavior.  Adam Levine, Andy Samberg, Kendrick Lamar and even Danny McBride made this a great digital short.  "YOLO" normally stands for "You Only Live Once," in this case, it stood for "You Oughta Look Out," as Samberg and his crew rapped about how you should never do anything remotely dangerous or risky, because you only get one life.