Acronym for You Only Get Murdered Once.
1) It is a proper counter-response to those who scream YOLO at very inconvenient and often inappropriate times.
2)exclamation describing negative and often hateful emotions to person who the speaker believes deserves neither happiness nor life.
Man 1: "Look at that bitch. I'm gonna go talk to her! YOLO."
Man 2: Did you really just say YOLO in real life!? Ugh. Y.O.G.M.O