#YOLO

The new carpe diem.

YOLO. Chances are good that if you know anyone under the age of 30 then you've heard them say this.

If you're a regular on Twitter, you've seen YOLO -- guaranteed.

If you do Facebook, you've seen it in hashtag form describing all kinds of craziness. YOLO is an acronym for "You only live once." Think of it as "carpe diem" for the digital age, and, over the last few years, it's arguably become the motto for many, if not most, of the millennial generation.

With eyes and ears now poised to spot it, don't be surprised when you see YOLO attached to all kinds of less-than-noble aims and activities. For many, the phrase "You only live once" is less of a motivation for meaningful living and more of a convenient, sometimes tongue-in-cheek, justification for fun, if not reckless, living.

You're most likely to see YOLO tagged onto a 140-character description of someone's antics while on spring break in South Beach, Miami, than on how hard they'd been studying for the SATs.

It's emblazoned on the...