Meaning You Only Live Once, it practically makes you believe you can do ANYTHING and you have the right to do everything, no matter how stupid. The people that say this practically enter derp moments.
Frank: Yolo. You. Only. Live. Once. Don't f***ing waste it. By the way, you are a real derp.
Note: These are random names.
As once heard in the 'deathcore' band Suicide Silence's song "You Only Live Once" it has been turned into a "hash tag" by Tumblr, Facebook, Twitter, and other social networking sites.
Kid 2: YOU ONLY LIVE ONCE!
SUICIDE SILENCE FTW!!!!!!!!!!!
You Only Live Once, so just go f..king nuts!