YOLO

abcNewsからです。以前留学生に教えていただいたYOLOという言葉についての記事を見つけました。

Young Adults Tweet #YOLO When They Don't Study, Get Drunk or Drive Too Fast

When 21-year-old rap artist Ervin McKinness died in a car accident this fall, his fans were quick to notice one final message from his Twitter account: "Drunk af going 120 drifting corners #F***It YOLO."

Less than an hour later, the driver of the car ran a red light, lost control and slammed into a wall, according to Ontario, Calif. police. Four passengers were pronounced dead at the scene. A fifth died at the hospital.

"What is YOLO?" was among the top searches in the United States this year, according to Google, but Twitter users certainly know what it is. It stands for You Only Live Once. According to Topsy, a Twitter analytics company, about 36.6 million tweets have included the YOLO acronym since it first appeared in October 2011 -- and a good percentage of them involved young people doing something dangerous or risky.

"There's something about the way the teenage brain functions that may tend to make poor decisions when other people are present," said child psychologist Dr. Mary Romano, who works at Monroe Carell Jr. Children's Hospital at Vanderbilt University in Nashville, Tenn. "Tie that into social media and even when you're alone, it almost artificially creates the presence of an audience because you sort of assume your actions are on display."

Over roughly three hours one morning last week, 34 people tweeted about the prior night's drunken antics with the YOLO acronym, an ABC News search found. A handful of YOLO-ers asked whether it was too early in the day to start drinking. Another 10 woke up that morning and tweeted that they didn't study for tests they had to take. Their tweets all included YOLO, or, as a Twitter hashtag, #YOLO.

"It was probably the most popular phrase on Twitter, I think," said Jamie de Guerre, the vice president of product at Topsy. He said Twitter users tweeted the #YOLO hashtag 388,000 times a day at the peak of its popularity in March. It's still used tens of thousands of times a day

Since the YOLO trend began, about 408,000 YOLO-tagged tweets had something to do with "texting while driving," according to Topsy.

Trumpeting dangerous behavior is part-biological, part-environmental, Romano said.

Romano said the part of the brain called the prefrontal cortex, which is involved in reasoning and planning, doesn't fully develop until someone is about 25 years old. And while the reasoning part of the brain is undeveloped, the thrill-seeking part of the brain thrives.

"In terms of why teens make risky decisions, there's biological evidence," Romano said.
http://abcnews.go.com/Health/young-adults-tweet-yolo-live-engaged-reckless-behavior/story?id=18027279#.UNXGiFuCiM8

YOLOを手持ちの辞書（『ジーニアス英和辞典　第４版』大修館）で調べましたが記載がありませんでした。
しかしこの記事によると、YOLOとは、You Only Live Once.の頭字語であることがわかります。つまり、「人生は一度きり」を表すのではないでしょうか。（Jakie）