A negative term used to refer to Mark Zuckerberg, founder and CEO of Facebook.
Mother Zucker changed Facebook's layout again. It was probably just a distraction to keep us from noticing the horrible privacy settings.
Basically means "carpe diem" for stupid people. It's an acronym for "you only live once."
Person 1: I yelled "YOLO" and ran out of class today.
Person 2: What are you, stupid?